Death Note/WMG

The Deathnote is a petition form to the Shinigami King, who is supreme God
All the rules of the Deathnote are the king's made up rules. It all seems like rules SOMEONE made up to make the whole Deathnote 'game' interesting. A game with no rules is not interesting. A game where Deathnotes have official 'owners' is.

The King of the Shinigami is...

 * Der Tod, from Elisabeth.
 * Well, he is frequently accompanied by "angels of death" and if he`s the king he does not necessarily have to follow his own rules. Maybe some of the rules were the result of his romance with Elisabeth.

There are other kinds of "notes"
First proposed humorously by Ben "Yahtzee" Crowshaw on his personal site. He speculates that there might be notes for other types of gods besides shinigami. He specifically mentions the Love Note, War Note, Rabbit Note, and Piss Pants Note.

The Death Note is really a mind-control device.
That would explain why Light can manipulate people into doing his wishes before dying. However, Ryuk and the sinigami wrote the instructions so the mind-control devices would remain Death Notes, in case if a Light-like sociopath took control of the world's leaders. (those leaders don't hide their faces, you know)

The real reason behind the ending of Death Note is ....... THE YAOI NOTE.
At the end Mikami possessed a death note and a yaoi note. However he mixed the two up, writing the members of the SPK and the Task Force's names down in the Yaoi note and writing his and Light's name in the Death Note. The Death Note in Mikami's saftey deposit box was also a fake to trick Near, he carried the real Death Note and Yaoi Note around with him all the time.
 * You made me think. What if really, the Death Note IS the Yaoi Note?! Think about it. Ryuk was carrying the real Death Note all the time, and while Light was writing all those names in his book, Ryuk could just look over his shoulder and write those names into the real Death Note, making it seem like Light was doing all those killings. However, in reality, the book that Ryuk gave Light is the Yaoi Note, which has the powers to make Light a magnetic to all yaoi pairings! You had Matsuda, whose admiration for Light is veeerrrry dubious; Mikami who worships Kira in more ways than we suspect; and who can forget L? This says it all. Also, this power extends to us viewers, so that we have no choice but to find yaoi in EVERY context, and search for subtext that is not even there to prove that Light and L are cannon dammit! Yes, the Yaoi Note should be feared.
 * Dude!!

All the recent celebrity deaths result from someone using the death note.
Michael Jackson died of a heart attack; most likely from the user was trying to make him do something that he couldn't do. Billy Mays was next... also of a heart attack! And then there's. "Michael Jackson: suspected of being a pedophile.
 * So what was the impossible thing MJ was supposed to do? Become a victim of black-on-black crime?
 * "Murdered by a Cute Beatle." Though it's starting to look like that entry read, "MJ: dies of anesthetic overdose."
 * Recent news says that MJ's death is a homicide. The police are just catching on.
 * Note the unusual airplane-related circumstances around the latter's death... a more successful experiment?
 * A lot of the recent deaths have been centered around California - and, more specifically, Los Angeles. As well, at least two have been killed by heart attacks (Billy Mays and MJ). And Los Angeles is significant because that's where Another Note took place. As well, there's been a trend of a celebrity dying every 1-3 days now. Gentlemen (and ladies), we may be onto something.
 * Steve McNair died today, as predicted.
 * Exactly as planned...tomorrow another famous person shall die. Justice is Kira! Another has died.
 * I was given this Deathnote by a man who looked suspiciously like Light, so that makes sense. My shinigami says hi
 * This just in: Ted Kennedy has died. Kira strikes again!
 * Two days later, DJ AM is dead!! OMG Kira's at it again!
 * Kira's on a Hollywood Rampage! Patrick Swayze dead at 57!
 * Oral Roberts is dead too, as of 12/14/09!
 * Kira only kills criminals, and this matches up.

Ted Kennedy: politician, and there's that Chappaquiddick incident.

Heath Ledger: did too good an impression of being evil in The Dark Knight.

Billy Mays: Damn, he's loud.

DJ AM: you saw how he died, right?

Patrick Swayze: Corrupting millions of teenage girls with his Dirty Dancing?"

s feels like a heart attack coming on. Candlejack! Come kidnap me and hit enter before I
 * This... More evidence! "Shame on you, Raito-kun"
 * Alternately, Zac Effron is the new Kira, who kills not for justice, but to slowly and steadily cleanse Hollywood of anyone and anything competing with him and his teeny-bopper revolution. That fiend!
 * In another few days, another shall die, the name written in my note book.
 * Tracing your IP now... wait, thi
 * Brittany Murphy has died at age 32 after suffering a heart attack in her Los Angeles home. Make of that what you will.
 * Now J.D. Salinger is dead! Am I the only one whose getting the felling that Kira is a Moral Guardian?
 * He can't have killed J.D. Salinger. [
 * Hey, it's just all apart of Kira's plan. He wanted to cleanse the world of evil by killing current criminals to stop them from corrupting others to have them repeat the cycle. In his mind, it's hollywood that's making evil look cool so people want to go over to the Dark Side. How many times have you seen the All Girls Want Bad Boys and Draco in Leather Pants tropes put into effect, and even been abused by fandumb? It's all cause of hollywood, so Kira is solving it by eliminating celebrities.
 * Andrew Koenig has died from suicide, and Corey Haim has died of a drug overdose. Celebrity Kira has apparently just discovered that he can control people with the note. And so his vendetta against The Eighties continues...
 * Ronnie James Dio - stomach cancer. Wow, I know, all the others, but HIM?
 * And now Brittany Murphy's husband has also died of a heart attack from "natural causes". At age 39. Clearly he got too close to uncovering the truth.
 * Kira strikes again. Probably cause of his assault record.
 * The Golden Girls, except for Betty White, have all passed away now. http://www.popeater.com/2010/06/03/rue-mcclanahan-dead/?icid=main|main|dl1|link3|http://www.popeater.com/2010/06/03/rue-mcclanahan-dead What does Kira have against old women? It's understandable for Bea Arthur (the abortion controversy on Maude), but the other two? Seriously?
 * Kira is a high school student in Massachusetts. Here's my proof: http://intimateviolencedeathnews.blogspot.com/2010/06/fitchburg-ma-fitchburg-teacher-dies.html
 * Randy and Evi Quaid, currently facing trial over vandalism charges, recently fled to Canada to escape a "celebrity death list" conspiracy that's already claimed Heath Ledger and David Carradine, and they fear may be after them now. Celebrity Kira's reputation continues to spread...
 * And I don't belive no one mentioned it, Leslie Neilson died a month or so ago. DAMN YOU CELEBRITY KIRA! SPARE THE COMEDIANS! TAKE STEPHENIE MEYER INSTEAD!
 * Wait, Bin Laden is dead? GOD BLESS YOU CELEBRITY KIR- Oh wait? Shot in a military operation, that's either a good cover or not related to Celebrity Kira.
 * *Death Note reads* "Osama bin Laden Headshot"
 * Isn't it a bit strange that the pictures of bin Laden's death haven't been released? Maybe the truth is they found him dead when they got there, and they can't let the truth get out about the real cause of death...
 * Kira strikes again to Amy Winehouse.
 * Kira strikes again, this time to Steve Jobs.
 * Are we sure it was Kira and not Ryuk? He thought he was getting an apple, not an Apple...
 * Kira strikes yet again, except now it's Whitney Houston. The cause of death as of this posting is 'unknown'. He's getting better at this.

A person's natural lifespan is the upper limit to when that person will die (barring suicidal shinigami).
In Another Note, Mello says that Beyond Birthday had an easier time with the physical aspect of killing his victims than most murderers because they were fated to die then anyway. This implies that most murderers kill people whose natural lifespan indicates that they should still be alive. Furthermore, this also explains how Misa was able to commit suicide even though she no longer owned a Death Note and had the lifespan of two Shinigami.
 * This must be true for the series to make sense. Otherwise, what happens if someone accepts the Shinigami eye deal in order to kill someone who was about to kill them?
 * The Death Note can screw with life spans all it wants. Obviously, if you make the eye deal, you're planning on getting the Death Note. The closest things to this situation in the story were the Naomi Misora incident and Higuchi trying to kill Matsuda; in both cases, they had enough time before their death sentences to act.
 * Jossed. Misa's lifespan was mentioned to be almost up on the day she was to be killed; it was extended when Jealous killed the man that was going to kill Misa.
 * You can also interpret the line this way. Most murders are killing without realizing they are participating in a kind of fate in the Death Note universe. Beyond Birthday is free of this. He was like Vriska in in that he was killing people that were going to die soon anyways and wanted to be the one who did it. Or more simply, replace the victims with horses. Average murders see a horse and have no idea if it is ill or going to live for years. They could be robbing years of life. Birthday knows the horse is lame and that the vet is on the way already to put it out of its misery. Why feel so bad over a few minutes or hours?

The Shinigami's World is Earth.
The distant future of Earth, or the Earth of another universe... a 'used-up' Earth no longer able to support life. The Shinigami are former humans who have extended their lifespans beyond all reason by the power of Death Notes. Who better to understand the futility of striving?
 * That would sort of fit with Rem's remark about Shinigami "evolving/degenerating" so much that they do not need food.

Shinigami have no idea whether humans have souls or what happens to them after death.
They're just predators of human lifespan who don't even understand half the things their Death Notes can do. It's clear that they have little consensus on the nature of minor things with other shinigami, and sometimes Ryuk just makes stuff up because it's funny. Ultimately, they don't care what happens to their lunch after they eat it.

The numbers displayed by shinigami eyes are meaningless
The rules of the Death Note establish that it can alter the lifespan of a person whose name is written in the note and that such changes aren't shown by the shinigami eyes. So if someone dies before their visible lifespan reaches 0, or doesn't die when it reaches 0, it may safely be assumed that someone used a Death Note to affect that person's lifespan. This, combined with shinigami lacking visible lifespans, makes it impossible to test the accuracy of the numbers. It is thus safe to assume they have no meaning. ""By manipulating the death of a human that has influence over another human's life, that human's original life span can sometimes be lengthened. If a god of death intentionally does the above manipulation to effectively lengthen a human's life span, the god of death will die, but even if a human does the same, the human will not die.""
 * Well, any meaning they had is lost now, 'cause Tsugumi Ohba forgot.
 * The big hole in your theory is that it's impossible to make someone live longer with the Death Note.
 * This isn't strictly true; Gelus extended Misa's life beyond its destined end (and sacrificed himself in the process) by using his death note to kill her murderer, the agent of her death. Rem also protected Misa by the same means: using the notebook to eliminate the human who threatened her.
 * Rem specifically states that when Gelus saved Misa's life, his lifespan was added to her own. This means that even though her lifespan had come to its natural end, Gelus' unnatural actions caused her to gain a new lifespan, which was equal to his own (which he didn't need anymore).


 * The number is not necessarily some sort of countdown. Even the creator said it was based on a "complex mathematical formula" which he "forgot." There is no reason for the number to get LOWER as a person approaches their death. There is no reason to assume it ever changes at ALL. Maybe it's a date as represented by the Shinigami calendar. It could be something like DAY / 12 x MONTH x YEAR + HOUR / MINUTE x 44.
 * Maybe it's an obscure branch of Death God math? Since people can't see the Death Gods without the Note, maybe the Death Gods are higher-dimensional beings? (Let's say fourth.) That would explain the general bizarreness of their appearances and outlooks; people's minds can only comprehend the first three dimensions. There's a whole new Ryuk out there! Since the Death Gods would be able to grasp fourth-dimensional mathematics, they could have invented something even more powerful than calculus to figure out when people are gonna drop?
 * The number represents how long the person would live naturally if left alone by the Shinigami.
 * Which still means the numbers are meaningless. Light killed off many murderers, many would have killed again. They couldn't, their future victims lived, thus changing the future.
 * Not necessarily. It's possible, probable even that when you die is when you die. If you were supposed to be murdered and can't you'll die of a heart attack.
 * I thought this was why the "can't kill for love" or whatever rule existed. The numbers are accurate barring interference from a Death Note. Any individual death may change other numbers. So a Shinigami is going to alter the numbers like crazy as they feed. There are just specific rules against abusing their life span changing powers intentionally.

Writing a dead person's name in a Death Note makes him or her Deader Than Dead
The rules of the Death Note state that a shinigami who brings a Death Note to the human world is obligated to confirm the death of the first human owner and to write that human's name in his or her Death Note. Since it's possible for the owner to die a natural death before his or her name is written in the Death Note, we must conclude that there is a reason for writing his or her name other then killing him or her - such as ensuring he or she stays dead.
 * This is why Ryuk killed Light when he was mortally wounded.
 * But Light wasn't yet dead when Ryuk wrote his name.
 * Pretty sure Ryuk was just doing it for the Lulz.

Humans can be killed before the end of their lifespan without a Death Note
One of the rules of the Death Note states that it's forbidden for a shinigami to kill someone without using a Death Note. If a person killed by a shinigami was destined to die then regardless of the shinigami's actions, there would be no way to justify this punishment.
 * Isn't a human being's lifespan their natural lifespan, with the death caused by an accident, disease, or other act of god, and not being murdered or harmed with the Death Note?
 * Another Note is vague on this point. On the one hand, Mello says that B knew the day his father would be murdered because of his shinigami eyes. On the other hand, Mello also says that the reason B had such an easy time killing his victims compared to other murderers was because they were going to die anyway.
 * Maybe B's victims were going to die anyway because B was going to kill them. B just didn't realize this.
 * Considering the fact that Gelus saved Misa from her predetermined death by killing her murderer, a human's lifespan takes into account murder as well. So, the Death Note would seem to be the only thing that can interrupt a lifespan since that's what it was intended to do.
 * Isn't it obvious? Shinigami can interact directly with the physical world (Ryuk confirms this at one point by mentioning that if he ate an apple, it would disappear visibly even though he is invisible), so the rule deals with them deciding, for whatever reason, to do things like "making someone compact".

The reason Ryuk calls the Shinigami world boring and rotten is human science and population
At the beginning of the series, Ryuk calls the Shinigami world rotten. He also thinks that it is extremely boring. The reason: human overpopulation and weapons technology are fundamentally making his job as a Shinigami worthless. The shinigami are a failsafe to keep the global population down so that we don't end up killing the planet. With all of our scientific advances, our population is growing much faster than it's going down; the Shinigami clearly aren't keeping up on getting rid of the excess people. Modern weapons make the Shinigami's job boring. With the advent of the nuclear bomb, the human race can kill millions of people (and possibly the planet) with a few orders and a handful of people. With all of this unnatural death - that is, humans trying to do what Shinigami do - it's messing up the (super)natural order of things.

The Death Note is merely a novelty item that is not magic at all.
All the deaths happened by chance.
 * The odds of this happening are about of one against 60 million for each death, assuming a mortality rate of 0.878% per year equal for everyone (criminals have a higher mortality rate, though) and a precision of one minute (it's closer to one second). The total number of deaths is unknown, so we can't get the chance of the whole story happening.
 * The theory is true nonetheless. You simply cannot argue with chance here. If you propose a causal connection between the book and the deaths, then you have to present a theory of the exact nature of this connection that would not only have to be able to be tested empirically, but would also have to be better than any theory of those deaths that does not propose such a connection. But the thing is: You cannot. All of the deaths are already completely determined by natural causes, and there is no visible connection between those deaths.
 * How Unscientific. You don't just throw away several years of data on an assumption that a trillions-to-one chance happened. The Death Note clearly just operates using undiscovered, but still scientifically testable, mechanisms. Attribute it to Sufficiently Advanced Aliens if you want.
 * Alternately, the Death Note has no inherent power, but Light is psychic. He's not causing all of those deaths, merely predicting them.
 * ...Or Light and the other Kiras had THE POWER all along and the notebook is merely a Magic Feather.
 * The multiverse theory states that there is are infinite number of universes with infinite number of rules. In that case, there would be two 'identical' universes, one where the Deathnote causes the deaths, and the other where the exact same events happen, but by random chance.

The Shinigami Realm is a Weird Trade Union.
Sure, Death Note Rule #36 is the most notorious for being Internet Rule #34 deterrent; but the others regarding Shinigami conduct reveal much further insight into what is essentially the local monopoly on supernatural causes of death:
 * Death Notes are issued on a one-to-one basis (barring bribes, as seen in the Extra Chapter). Killing a human without using a Death Note is considered an Extreme-level crime whose punishment is concluded with the death of the offending Shinigami.
 * Strict timetables are set for the possession of human Death Note users and recovery of Death Notes that have been relinquished from the human realm. But there is no timeline for the retrieval of a Death Note owned by a killed Shinigami - while the rules recommend returning it to the Shinigami King, the common practice is "Finders, Keepers."

The Shinigami of Death Note and the Reapers of The World Ends With You are part of the same organisation
Think about it. They both consume human lifespans to survive, both abide by strict sets of rules, and both have a habit in meddling in human affairs. The Shinigami affect the RG and send people on murderous rampages with the Death Note; the Reapers affect the UG and run the Reaper's Game.

Humans who use Death Notes become Shinigami when they die.
This gels nicely with Ryuk's comment that a human who uses the Death Note can neither go to Heaven nor to Hell. It also explains why shinigami only know bits and pieces of what a Death Note can do -- all they know is what they figured out while they were alive.
 * In the manga, it says that all humans go to nothingness, not just the Death Note users.
 * That does weaken the theory somewhat...still, is there any evidence that shinigami aren't what becomes of humans who use Death Notes?
 * Ryuk isn't the most trustworthy source for information. He's deceived Light in the past; there's no reason to think he wasn't deceiving him then.
 * Possibly, there are two nothingnesses: Purgatory for normal humans, and the Shinigami Realm for Death Note owners.
 * I don't think you understand the concept of "nothingness".
 * Maybe you only become a Shinigami if you have used the Deathnote and have the right kind of personality for it. If Light did indeed become a Shinigami, then it would be due to his past experience with it and the fact he has no qualms with using it. Raye Penbar, on the other hand, wouldn't become a Shinigami because he didn't know what he was doing. He doesn't seem like the kind of person who would willfully use the Deathnote.
 * Maybe only humans that use Death Notes to try to become God become Shinigami? Shinigami die by falling in love with a human, right? So if they were only humans that had used a Death Note, perhaps by accident, like Raye Penber or Light in the pilot, this wouldn't make sense.
 * Or maybe when a deathnote-user dies and becomes a shinigami, they forget about everything 'except' the deathnote, sort of the opposite of when they discard a deathnote.
 * Only Death Note owners become shinigami, not just Death Note users. Therefore, since Raye Penber never owned a Death Note, he's not a shinigami.
 * The Shinigami not knowing about the Death Note is put down as a "too cool for school" attitude. They can get a rulebook any time they want; they're just too lazy.
 * Before Rem and Gelus' deaths, there had always been 13 shinigami. Afterwards, there were only 11. When Light starts using the Death Note, he is put in the running for becoming a new shinigami. After he loses his memories, he's still the next choice until Higuchi (the business man?) starts using the Death Note. When Light regains his memories, he kills Higuchi and, in theory, beats him in the 'game.' Light could have become Gelus' replacement because of that or because he had a higher body count. Misa is supposed to have commited suicide around the end of the series, after Light's death. She would have become Rem's replacement (the replacement female shinigami). If she didn't, Mikami could have, since he also had a higher body count than both her and Hiuchi. He could have been Rem's replacement, since he wasn't as used by Light as Misa was.
 * Then, you could think that the 'nothingness' that humans go to IS the Shinigami Realm, as in, the Shinigami Realm IS nothingness. That would explain the barren look. Or, as someone else said, there could be two nothingnesses: Purgatory and the Shinigami Realm. Evryone who didn't manage to beat the 'game' or other 'competition' to become new shinigami could have gone to Purgatory instead, save for Mello, who probably never used his notebook.
 * In the manga, Ryuk specifically states that you go to mu when he says you go to nothingness. Mu is not Purgatory. Mu is an eastern concept for which the closest description I could give for it is "null". It means less than zero. Less than gone. Less than nonexistant. Going to mu means you become null; you simply cease to be.
 * Also, that shinigami that spoke with Ryuk in that one special episode mentioned earlier also threw Ryuk an apple in the same way Light used to, and wears some kind of weird tie and suit getup, which could have been some kind of skewed version of what Light wore in life. There's a picture somewhere on a Death Note wiki.
 * Here you go.
 * The clothing thing would also make sense, since the other shinigami have human characteristics to their attire. One wears an Indian chief's headdress (the book can be dropped for anyone to pick up and use in any time period); another is covered in gold and wears a crown like a rich and greedy king might have. But, that also brings into question that fat slug-looking one that likes bananas from the extra Death note chapter and the other shinigami that's covered in eyes, though they could have been a fat or gluttinous woman and a voyeur.
 * Rem was a pharaoh, or some other high-ranking egyptian, who used the note to gain power.
 * Maybe Rem was Hatesphut?
 * This being true, Ryuk is actually Light from the future after he becomes a shinigami. He gave the Death Note to his former human self, establishing a stable time loop. Think about it. They're both sadistic, manipulative liars. That's why Ryuk is constantly amused and having a good time. He knows how it turns out.

Death Note owners immediately cease to be human.
It's possible that owning a Death Note transforms you into a Shinigami inhabiting a human body. This would explain Light's Shinigami-like appearances later in the series. When you die, you leave the body as a Shinigami living off the additional lifespan you garnered from lives taken by the Death Note. "Ryuk: Don't worry Light, you're already a worthy Shinigami..."
 * Death Note users become "proto-Shinigami"; this explains Light's flashing red eyes and his ability to run a marathon after being
 * Shinigami eyes cannot see the lifespans of Death Note owners because they "become hunters instead of prey."
 * Also there's this when discussing the eye deal:

"No Light, you weren’t God back then. You were something else... You were just already... {dead / gone}..."
 * Both the manga's "several years later" one-shot and anime's "director's cut" special show the shinigami and their world a while after the events of the series. Light does not appear, and the shinigami openly discuss him in the past tense. There might be mention of something like this is an interview with the author, too, and it was rejected there as well.
 * Unless you assume that IS Light talking to Ryuk and feeling nostalgic. It's a common framing device.
 * The way Ryuk said "Light" in the end strongly suggests that Ryuk was talking to a Shinigami Light the whole time. This also explains why that shinigami cared about Ryuk's adventure -- he could be Light with a fractured memory wanting to know the truth.
 * This troper has seen Ryuk's final lines in Relight translated a couple of different interesting ways:
 * The biggest proof against this is Raye Penber. He used the Death Note, too; if humans who use Death Notes become Shinigami, then you'd think he would have just killed Light, especially since Light went after.
 * He only used a page of the Death Note. Just like with the memories, one must possess the entire note for it to count. As it stands, Raye only wrote the names in.
 * It's logical to assume getting killed when you are human (or a Shinigami-inhabited human) ends the ownership of the Death Note you were using then, thus robbing Raye of his Death Note related memories, including those of Light killing him. Also, killing Light might be Shinigami-suicide, since it would have been done with the intention of saving the lives of thousands. Raye may not be willing to embrace what we could know in his Shinigami state to be oblivion.
 * Another possibility -- the lifespan was given to Light, not Raye; thus, Raye didn't become a Shinigami

== The more bug-like shinigami, as mentioned in How to Read (such as the slug-one and Sidoh and possibly Gelus) are the original Shinigami, or at least pre-human; the more human ones (Ryuk and the unnamed shinigami and possibly Rem and Gelus) used to be human. ==

Shinigami pass on to Purgatory when they "die"
In conjuction with the theory above, when Shinigami use the Death Note in order to save a human life, they redeem their souls, leaving the Shinigami Realm (which is Hell) and finally passing on to Purgatory (and then to Heaven, or the "human" afterlife). Shinigami are formed by usually corrupt and greedy people who have owned and used a Death Note in the past for their own gain (e.g., Light); it usually takes centuries before any ever redeem themselves, if it happens at all, but showing that they come to care for a being other than themselves returns their humanity, reducing them to a form indistinguishable from dust or ashes as they pass on. As per their wishes, the human they have saved receives their remaining life span and lives on while they die so that they won't continue saving them. This is why many don't know how a Shinigami dies, let alone how to kill one: it is rare for it to happen, or for any Shinigami to see it when it does. Rem just happened to be at the right place at the right time when she observed it.

After some period of time, used Death Note pages are erased, repaired, and returned to the note
This is why all of the Death Notes remain the same size.
 * Alternatively, the pages are biodegradable (which makes sense, since they're already combustible) whenever they're outside the binding of the Death Note. Removed pages grow back up to the amount the Death Note was originally bound with.

The Death Note can do the impossible.
One of the rules says, if the written cause of death is impossible, then the victim will die of a heart attack. Taken at face value, this means that the victim will die of a heart attack even if it is impossible for that to occur.
 * Since a Death Note can cause circulatory failure in humans without hearts (not necessarily The Heartless, but you get the idea) or with artificial hearts, it can make the impossible possible, and is thus Mwu La Flaaga. Or Kamina.

The "fake" Death Notes one can buy online are real.
However, due to the 6 Death Note rule, they aren't functional -- yet.

Tom Anderson and/or Mark Zuckerberg own a Deathnote

 * And now they`re encouraging everyone to disseminate their names and faces in public...

Death Notes have an opposite number, the Life Notes
They cause instantaneous pregnancies.
 * The last remaining one was destroyed after the conception of Christ, however, once the Bible Black finished beta testing.
 * All but a single piece, where Shmi Skywalker's name has been written.
 * So, writing a man's name...
 * ...will get you this.
 * Maybe he will just impregnate the next woman he has sex with - no matter which contraceptive they will use

All Death Note users (and humans, for that matter) go to Mu when they die.
Sadly, Ark took the last Enbu Pike, so they're on their own.
 * Or maybe we all go to Tales of MU when we die.

The Shinigami eyes...
Are really Mystic Eyes of Death Perception. While Shiki had been trained as an assassin at birth, he identified death as 'lines'-something he can cut that is, make happen. To anyone else, however, they simply identify death as an 'event', mostly beyond their control, meaning they can only see a timer counting down until the persons predestined death, and a name to distinguish that death from any other death. Since the people who gain the eyes aren't the sort to comprehend the 'death' of an inanimate object, they don't get the lifespans of inanimate objects. And since they don't see death in anything but the living, they don't get the splitting migraines Shiki suffers from.

There really is an afterlife
It is just called MU, or nothingness. Naming it that was just one of Ryuk many jokes. And it is not like this series does not already have weird naming conventions.
 * Even worse, it turns out "MU" actually stands for the Marvel Universe (A fate some would argue is even worse than an existence of nonexistence). And with so much disaster and no Death Note in existence there, any Death Note user is screwed.
 * This troper thought that, from the capitalization, the above troper meant MU. Which this troper originally read as "Tales of Nothingness." It has no support whatsoever, though.

Humans will be the next shinigami.
In How To Read, it's mentioned that the designs of the shinigami were based on insects. Since there are only 13 shinigami (plus The boss), and at least two shinigami died in the space of a year, there will eventually be no shinigami left. The remaining shinigami will either be bored like Ryuk or infatuated with humans like Gelus, only the Ryuk-like shinigami will make a mistake and get themselves kiled. As Ryuk is the only one to successfully (sort of) pull of a "get more Death Notes" plot, he will replace the god-being once the other ten shinigami bite the dust, and any humans that have or have used death notes and survived, or have received the shinigamis' remaining life spans (see: Misa Will Live For Hundreds of Years above) will replace the shinigami, and frow to be more like the beings that replace humans, as the original shinigami may have grown from insects.

Only as many death notes may be used in the human world as there are shinigami.
Six shinigami died, possibly including Gelus, but Ryuk either didn't know or didn't bother to update the rules after Rem died.

The 23-day rule applies even when the cause of death is a disease.
The reason the rules state that it doesn't apply is due to a misunderstanding about how the 23-day rule works. Rather then having 23-days to kill the victim, the Death Note has 23-days to cause the victim's death. For instance, if the cause of death was a disease that the victim couldn't possibly contract in 23-days he or she would die of a heart attack.

Everyone who dies is reincarnated as a cow.
Mu is just a misspelling of "Moo".
 * No, it's the German spelling.

It is possible to kill Shinigami by mundane means
The rules of the Death Note say that shinigami cannot be killed via a stab to the heart with a knife or a gun shot to the head. Note that it doesn't say what would happen if you say shot the in the heart, stabbed themin the head, or nuked them, or well you get the idea. However, due to their ability to become incorporeal, hitting them would be quite difficult.
 * They can't be killed by human means, but seems like natural causes like starvation and stuff do affect them; it might not kill them, but causes plenty of pain and suffering.

Shinigami are asexual.
The whole male/female thing is just due to their social behavior and body shape, not due to a presence of sexes. That's why they can't have sex with humans. As for being the receiving side in anal sex... Let's just say it's not compatible, okay? I don't really like to think about that. Neither should you.
 * Asexual is not agender.

The shinigami each correspond to a major character.
Ryuk is L/Ryuzaki; He does all this because he's bored with his power over humans (which "he" doesn;t matter). Mello is Rem, full of rage and emotion to the point he/she/it can't do their job correctly, and hates with a passion Ryuk/L. Gelus is Misa; obsessed with another character to the point of self-destruction (especially if you consider the "after the series" information from How To Read). Near and Sidou are mostly but not entirely paralell: both dull and uninteractive, and want to get rid of their primary opposition (Ryuk for Sidou, Kira for Near), but Near is presumably very smart compared to the others, whereas Sidou is... not. Light, of course, is the Unnamed Shinigami.

The Shinigami King is the unnamed shinigami.
He could have taken on a form reminiscent of Light to mess with Ryuk, something (Ryuk or the Death Note power) pushed Light gently towards similarities to the Shinigami King, or it was just coincidence.

The Death Notes have a kind of influence on their user to ensure they are used as much as possible.
Think about it. Light, mid-Memory Gambit, was much less evil-seeming than he was even in his first couple of days in possession of a Death Note. Nobody corrupts that fast naturally, it just doesn't work. Not to that degree. And then there's Misa, who's much more crafty and overall intelligent when in possession of a note and trying to get to Light than at any other point, even immediately after she surrenders it to Light - as The Ditz, she wouldn't have used it at all, therefore the note made her smarter to encourage use. The notes are meant to be used, and will be. No matter what. (And before you accuse me of crafting Light some leather pants, the only pants I'm interested in are L's. Er... That Came Out Wrong...
 * Using a death note = using crystal meth?
 * MY PRECIOUSSSSS!!1111

Only people who have shinigami eyes when they die become shinigami.
Because by the time they die they already have a shinigami body part (metaphorically speaking). So by that logic, B, Higuchi, Soichiro, Mikami, and the unnamed kid from the three years later affair become shinigami.
 * In the movieverse, that means only Takada became a shinigami. And maybe B. It's never outright stated whether the LABB case happened in movieverse or not.
 * It's mentioned early on in the L movie
 * And the L movie's canon?
 * Only for the movieverse

The Death Notes are a type of zanpakutou
Think about it. Their wielders are shinigami, and they have special powers. They're just like Ichigo's and Kenpachi's zanpakutou: always released on shikai, which takes on the form of a notebook. They were probably developed by Mayuri as a way of sending pluses to Soul Society without having to bother hunting them down and doing that release ceremony. But something went wrong, and they became able to drain the reiatsu of living humans to their wielders, which then turned evil and went on to live in hueco mundo. Thus, all the Kiras are in fact shinigami, who'll turn into hollows when dead, since their hearts are already lost. One can only wonder how would the death note's Bankai look like.
 * Eyebeams that kill people and drain their life
 * That's kind of a step down from killing any one in the world just by writing their name down in a notebook.

Humans don't actually have anything written above their heads.
The Shinigami eyes actually link the user to a Magical Database equipped with Facial Recognition Software. However, that database only contains records of living persons. Thus explaining why a person's name and lifespan can only be seen in a photograph if he/she is still alive.

Some of the "official" Death Note rules are actually lies made up by Ryuk
Ryuk wrote down the instructions to begin with, and is perfectly capable of writing down false ones as he showed Light. Taking into account that he's not bound by human morals or commitments, it's possible that he made up fake rules to add to his entertainment or cover up what he didn't know. The next three WMGs take this into account.

Death Notes can control people well beyond 23 days before their deaths
In fact, they can influence peoples' lives for years, as long as it ends in their deaths. Ryuk, however, didn't think it would be fun to watch anyone's death drag on for years, and claimed that there was a time limit.

Erasing a name in the Death Note CAN bring someone back to life
...provided not enough time has passed since death and the body is still functional. Of course, doing so would mean forfeiting the user's life. Ryuk never saw the point of this, and couldn't imagine a Shinigami ever trying this, so he simply wrote in the instructions that doing so is impossible.
 * You need a special eraser to do it.

Killing people with a Death Note can extend the user's lifespan, even if he is human.
Ryuk simply decided not to write it down so that the human wouldn't act like a Shinigami, killing only once every twenty years or so for insurance. Better as many deaths as possible. Because of this, Light could have lived for hundreds of thousands of years - and all of it went to Ryuk after writing down Light's name. Lucky Shinigami never has to work again!

The Death Notes hone in on humans with similar personalities to that of the Shinigami they are attached to.
Let's see you got Ryuk and Light- manipulative liars who don't tolerate boredom well (and bonus points: having the exact same inner monologue at the start of the series! Both believe in "This world is Rotten"), Rem and Misa both have their tragic love, and Sidoh the wimpy Shinigami ends up with Snyder the wimpy mafioso.

Alternatively, the bond with the Shinigami has a subtle influence on the owner's personality.
Light is much more playful when he is attached to Ryuk and more prone to slashy moments when attached to Rem. And in Season 2 after being attached to Ryuk for a few years Misa is even more hyperactive than before and is often complaining about how bored she is.

There really is a Shinigami Wing Deal.
But the trade is for something so horrible that no sane user would ever consider it.
 * I'm in
 * This guess now comes in fanfic form. (NSFW, Yaoi, Crack and making HP Lovecraft cry.)

Death Notes regenerate.
It is impossible to permanently destroy them.

Those with shinigami eyes have one of two choices: insanity or suicide.
While it may be handy to have when one has a Death Note, shinigami eyes-and knowing the names and lifespans of everyone one meets-have to take a toll on a person's mental state after a long time, causing them to either lose their minds completely, or killing themselves to make it all stop. Third Option: Blinding oneself Oedipus style. Pretty much all the examples of Death Note-B, Higuchi, Takada (live action only), and Mikami- went insane. (The kid from the one-shot killed himself, but for unrelated reasons, and Soichiro didn't live long enough to get any option.)
 * Wasn't there a rule somewhere that said those who traded for the eyes had them "forever" unless you forfeit ownership of the notebook? So if you attempted option 3 wouldn't they just grow back?
 * That's if they decide to forfeit, but consider this: B never had that option. He was born with shinigami eyes. Now, maybe he's just a one in a million baby, but if there are others out there like him, born with shinigami eyes, it's more likely that they'd do one of the above.

Contact with a shinigami erases morals.
This is why Light screamed when he first saw Ryuk; it wasn't shock, it was the pain of having part of his mind/soul/whatever-you-want-to-call-it ripped away. This is also why Misa's reaction to Rem telling her that she and Light were Kira was so amoral even before she regained her memories; simply being able to see Rem did the same to her. When someone loses the Death Note, they aren't being possessed by the shinigami, and they're no longer influenced by them. The shinigami themselves probably don't even know about this, except for possibly the King. This is why shinigami have to stay around the people who are holding their Death Notes. And who knows what the long-term exposure might have ended up doing to the task force?
 * Maybe that's part of why the Kira investigation stalled for five years.

Only Death Note users who are killed by shinigami can become one
If we're to accept that the unnamed shinigami is Light, then we gotta ask what made him so special out of all the kiras? The answer is all of them, except Misa, were killed by Light and not one of them were killed by a shinigami. Hell, Light or Near probably killed her too

The Death Note could be used as a part of a perpetual motion machine.
The Death Note never runs out of pages. Burning those pages portions at a time could be used to create a fire that would create more energy than what was put into it.

When people die the go to the Pokémon world.
MU is just a misspelling of Mew. When you die you go to the world where Mew lives.

The Death Note really was just a prank.
But when Kurou Otaharada coincidentally died when he tested it out Light was driven insane because he believed he killed someone. The rest of the series is his hallucination with the exception of L who he knows as another inmate (friend / rival / more-than-a-friend) at The Home for the Mentally Disturbed and who Light has incorporated into his delusional narrative.

Mu was actually closer to a proper afterlife once upon a time.
However, the Shinigami stopped giving a crap about their jobs at some point and let the realm fall into disarray. As a result, the afterlife became The Nothing After Death.

== Unwritten, unspoken law of the Death Note: If, while writing someone's name, the Death Note user slashes their pen dramatically in the air in a certain direction, the person will, if at all possible, fall in that direction when they die. == This just has to be a rule. Possible reason for it: because the Shinigami like their dramatic montages almost as much as they like their gambling and apples.

L had supernatural powers
L possessed some mind-reading powers and could also predict future, he just needed to focus on something and if this something is human he read his mind (but couldn't see with his eyes), or if it is event or idea he saw near future in third person perspective. However he was smart enough to maintain cover so the problem was not to find who committed crimes, but how to tell others without being suspicious. He could tell that Light is Kira from the very beginning, but had to start investigation to draw no uncontrollable or unwanted attention to himself. However he couldn't read shinigami's minds and probably knew that, this explains his freakout when he learned that shinigamis are real. And yes, he heard all Light's internal monologues but needed irresistible evidence or Light's personal public confession to arrest him, and also it was hard for him to accept Death Note as Light's weapon. While Light was losing to L all the time L missed exact moment Light set events leading to his death in motion but all he could do by that time is to call someone from Wammy's house as his substitute. In the Wammy's House kids with such abilities were gathered, or normal orphans were infused with such powers and than their development observed. Stronger skills lead to subjects matured much slower. Near also had such powers, but probably not fully awakened or just a bit weaker than L's, however he was much less subtle with their demonstration because he was less experienced in using them, much less known in the world and had full support of his team, while L was all the time under suspicion by members of Taskforce, despite being stronger. Mello, on the other hand, was much weaker than L, but probably was smarter than Near himself and so was with him almost on par. This also evens balance of power, making Light's struggle look much more impressive. Sorry for my English

L was born with the Shinigami eyes.
Yes, just like Beyond Birthday. They could be brothers or something. That's why L knew Light was Kira from the very beginning—because he saw no numbers above his head. However he couldn't arrest him just based on that. How would he explain it to the police (and Light's father)? So he had to find the physical evidence in order to substantiate his "hunch."
 * But if the lack of evidence is solely based on the supernatural aspect of this, then shouldn't he just reveal this to the police when Death Note and shinigamis become involved in the investigation?
 * They learned about Death Notes and Shinigami but they didn't know how the Shinigami eyes worked, and L was probably ashamed of them, considering what happened to B. He was afraid that if he told anyone about them that they would think he was crazy, or worse a Kira. Remember how paranoid L is and how manipulative Light is and how the investigators want to take Light's side because he's the Chief's son. If L revealed his powers Light might twist it so L became a suspect in his own investigation.

L is slightly obese
There's no way that someone can eat that many sweets and get away with it. L isn't too fat, but he has a layer of fat that he doesn't want anyone to know about. That's why he avoids tight clothing and spends his time hunched over.
 * I eat like L, plus copious amounts of fast food and soda, and I am thin. L just has a high metabolism.
 * I binge eat, and I weigh 96 lbs. Trust me, L just has an insane metabolism.
 * No, the reason L is so thin is because he burns calories by thinking.

L is on Crystal Meth
He eats insane amounts of sugary foods, and is still really thin. Saying he has an insanely high metabolism is a bit of a stretch. And when you factor in the fact that he never sleeps...yeah. And he says that he burns the calories with his brain activity, yeah right.
 * Technically he would have an insanely high metabolism.
 * He may also be using any legal or illegal substance that would increase his metabolism. Claiming one can get away with eating anything if you use your head could be a reference to a deep understanding of biochemistry and exercise science to the point where he determined the perfect combination of drugs and suppliments that he was willing to use, as well as times of day and understanding of his own metabolic cycle and how to manipulate it through adjusted sleep patterns, psychosomatic control over his own bodily functions, knowing how to trigger different states via physical stimulation to trick his body into using up specific nutrients without storing them as well as getting most additional fats and carbs to pass through his system too fast to be fully digested.

Light is stuck in a time loop.
In the last episode

Light is Doctor Horrible.
"The world is a mess and I just need to rule it!"
 * ...and L is Captain Hammer, Misa is Penny, and Ryuk is Bad Horse...

L is really Lelouch Lamperouge.
Filling in the blanks of L's Dark and Troubled Mysterious Past. When Lelouch was very young he runs afoul of someone with a teleporting Geass and he lands in an Alternate Universe where the Britannian Empire never existed. He's found by inventor Quillsh Wammy who creates the necessary Applied Phlebotinum to get him home but Lelouch never forgets about that kindly old man or that other world where the people are free. Flash forward about ten years later after Lelouch goes through with the Zero Requiem plan. Through someone else's Geass power or some other Applied Phlebotinum he's  Fearing that this will undo what he sought to achieve he escapes into that alternate world he discovered when he was young and reunites with Quillsh Wammy, where he takes on a new identity as the Great Detective L. But he's still very depressed and   So, he never goes out, his hair grows long and he wears the clothes of a commoner. He spends all his time solving cases and since he has horrific nightmares from the war he tries to avoid sleeping, and begins eating massive amounts of sweets as a nervous habit. He takes on the Kira case partly out of a desire to stop him before he can create an Evil Empire just like Britannia but also out a subconscious hope that Kira This is why L zeroes in on Light immediately, he recognizes a kindred soul, a Machiavellian bastard just like him or his family.
 * Or maybe because Light reminds him of Suzaku and Rolo.

'L' was born Elle, a woman
What is the most perfect way to find your identity? Change your gender! Seriously.


 * If someone was trying to find out who he is, they would find out about a little girl named Elle Lawliet who had disappeared, not L Lawliet.
 * If there were any childhood photos, no one would have presumed them of him as it would've been a small female in the picture.
 * Some of his eccentricities could be pointed to female habits. L doesn't seem to be the type for bras and if he had a large chest on a small growing body, it could hurt his back, giving him a slouch. Similarly with his sitting posture, he might have gotten painful period cramps and curled up like that which developed into a habit.

L is a girl.
See above Guess. She could just have a deeper voice... maybe (as per another Guess) from being a former smoker or something... That's why she wears baggy clothes-to hide her true gender.
 * Rule 63:, ,

The entire series was a hypothetical exercise for L.

 * L heard about the Death Note through the Taro incident in the pilot. He immediately began to worry about the possibility of a Death Note murderer, and set up a hypothetical situation to prepare. He began in the worst case scenario: He had no knowledge of the Death Note and it had come into the hands of his only intellectual equal. From that base, he began thinking about what events would happen and how he would deal with them. When he got bored, he threw in new elements like Misa and Rem. Eventually his hypothetical Kira outwitted him, and continued the simulation with his students.
 * Trust me, that makes me feel so much better.

Death Note is just a Strategy RPG video game that Light is playing and the different ending of the manga, movie, and anime are the result of his Save Scumming.
Light developed the game himself and the personalities of the enemies are based off his good friends L, Mello, and Near to annoy them. Light tries playing his game and the first time... And L is there  to tell him he needs to stop fooling around—they have orphans to bake cookies for and besides, it's Matt's turn to use the Xbox-he wants to play Grand Theft Auto and

L is a robot!!
Rem didn't want to kill L, but did so inadvertently by killing Watari. L gave instructions to Watari to delete all data when he died, correct? It's because L is a robot. L needed someone to guide him at all times, and Watari was that person. When Watari pressed the delete button, it stopped L from functioning, which killed him as well.
 * But if he's a robot, then how come Misa can see his name and lifespan with the shinigami eyes?
 * Possibly either a lookalike, or the person whom the robot was based upon.
 * A lookalike with the exact same skills and knowledge as the robot?
 * Hey, even if L is a robot, he's still a person. And not even robots last forever. (The warranty runs out sometime.) So he does have a lifespan, and it can be detected. And he does have a name. Hey, L is a more fitting name for a robot than for a human, isn't it?
 * He's a Cylon and
 * He was a very convincing robot built by the  who definitely has the intelligence to design a robot in his own likeness that can fool even the Shinigami eyes. I bet even now,   is sitting back at home in his comfy little apartment somewhere, eating all the cake, surfing on the net and reading over everything we're reading. In fact, he's secretly signed on as a troper, just so he can monitor what we say and then edit our responses to make sure that if we ever do get too close to the truth, he can remove it immediately. In fact, he's already changing things as we type. He's invited a secret code called "troper speak" where everything is explained in ridiculous lines that otherwise make no sense in the context its used in, like Lampshading. Only those of us tropers smart enough bother to decipher this code continue to try expose the truth of Robot L and his master.
 * All of the above is ridiculous. I, I mean L, would never do any of that. The idea of that is absurd!
 * So.... Actually a Doombot? (OMG L is Doctor Doom!)

L's biological parents were fans of The Slayers
They named him after their favorite character, L-sama.

Light is gay or asexual.
First of all, Misa was throwing herself all over him from the second they met, and he didn't seem to care. Later, she began wearing the skimpiest things imaginable when they're alone; again, he doesn't care. He's never shown any interest in women beyond their usefulness to his plans (Misa and Takada for their willingness to follow him completely, the girl he took to Spaceland, etc.). He even said something to the effect that all the girls in his school want him, but he only sees it as a way to help in his plans. All this is understandable after he obtains the Death Note; all he wants then is world domination. But one would think that, being so popular, he would have had a girlfriend before he found it.

And then there's all the things implied between him and L...
 * Then there's his selection of Teru Mikami, who's fanatically devoted to him AND bears more than a passing resemblance to L.
 * "Yagami" backwards is "I'm a gay." Make of that what you will.
 * "Yagami" is his 'surname', so that wouldn't be relevant unless his whole family is gay.
 * Light's mother and sister do show more interest in Light's girlfriends than he does. His father does spend a lot of time (days, even weeks) away from home with his all-male team of investigators (the live action movies add a token female).
 * Maybe "Light" is short for "[[http://www.urbandictionary.com/define.php?term=light
 * 2:35, "You can't blame us for thinking it."
 * Look at an above statement about the Yaoi Note. I believe that helps explain for this section too.
 * No mention of Light's apathetic staring at porn to appear normal to the cameras, L, and the police? He specifically buys said porn for this purpose, highly implying that he did not have it to begin with... He even tells Ryuk all this with a bored, almost "kill me now" face... What 17/18-year-old teenager doesn't have some form of porn? Even Light should have attampted experimentation...
 * Looks like this one is canon. In How To Read 13 the author states that "Light is incapable of loving any woman." Though whether that's because he's gay, asexual, or too much of a sociopath to care is left up to the reader's interpretation. However in that same paragraph it also states that Light is not totally lacking in empathy like a sociopath because he genuinely cares about his family and humanity as a whole. So that leaves us with options 1 or 2...

Light is not Asexual or gay, but would only be interested in a specific kind of woman.

 * Specifically, a quiet, stoic woman as smart as Light himself who would understand his motives and aid him of her own accord (without having to be manipulated). She would have to truly believe that Light deserves to be the criminal-purging God of the New World and agree to be his permanent Dragon for when he's too busy. In other words, a Distaff Counterpart of himself who wouldn't try to overthrow him. Neither Misa nor Takada fit the bill (both of them obeyed him out of blind love rather than true understanding of his motives).

Even then, the relationship would probably be non-sexual, and Light's priority would still be himself.

Alternatively...

Light is in love with HIMSELF

 * Wouldn't surprise me.

L has Asperger's Syndrome.

 * I've heard this one many, many times...

Light realizes what a bland and uninteresting character he is, and sets out to kill anyone more interesting.

 * Once Light gets the Death Note, he goes on a murderous rampage. But then there are characters like his dad, Ray Penber, Ray's fiance Naomi, L, and, well, everyone else. His only course of action is to kill off anyone that could be more interesting than him so he can be the most interesting person in the world. Unfortunately, that didn't work, because he's still less interesting than Naomi.

The real reason L challenges Light is because of fandom rivalry.
Because Light is a Bishonen bad boy who has a personality beyond being "mysterious" and that just won't do! Being "mysterious" is L's whole shtick- so very mysterious, and dark, and brooding and mysterious. Yeah, that's L's real plan-to attract scores of fangirls with his troubled brooding and the way he eats sweets.

Light is genuinely working for Justice, and L and co. are servants of evil.
As The Good Book Says, John 3:19-20: ''This is the verdict: Light has come into the world, but men loved darkness instead of Light because their deeds were evil. Everyone who does evil hates the Light, and will not come into the Light for fear that his deeds will be exposed.'' Therefore, by seeking to capture and stop Light, L. and company are the real evildoers.
 * You are Light, aren't you.
 * That's impossible. Completely ridiculous. I'll need a full name and some photo ID, please...
 * Feel free to ignore the fact that the entire Christian doctrine is based on forgiveness, of course. And the whole "love your neighbor as yourself" commandment, or the whole "Jesus dining with sinners," shtick, or the "forgive us our trespasses as we forgive those who trespass against us."
 * Then what explains the "Eternal punishment" schtick in the bible?
 * Also, Lucifer literally means "bringer of Light". Make of that what you want.
 * Lucifer IS Light. Can't say it's just a mere coincidence. Actually, the whole "Kira" thing is for Light/Lucifer to create a whole world where he has taken all of God's children and has become God over them. What better way to piss the big maker in the clouds off? The arguments below go into better detail for further explanation.

Light is the Antichrist.
His name is written with the kanji for "moon," and thus the pronunciation of his name is simply a way to deceive us. And let's not forget who, in The Bible, the "Lightbringer" was, and who tried to place himself Above the Most High.
 * If Light is the Antichrist, L might be Christ.
 * Satan/The Devil/Lucifer is NOT THE SAME AS THE ANTICHRIST.
 * True, but the argument can be made that Light is The Dragon, aka Satan/Lucifer/The Devil, and that Kira, his identity, is The Beast. Light brought forth Kira, in a ways, and the people of the world began praying to him - or rather to Kira. Rather than two separate beings, if one considers that the Dragon and Beast are two halves of one being, then the idea that Light, or rather Kira, is the Antichrist begins to make sense. The Beast or antichrist is also a metaphor for a One World Order, and Kira did put the world into a One World Order through fear and mercilessness, contrary to "Love thy neighbour". It also helps that Misa can be seen as the Whore of Babylon - a pop idol who worships Kira and is beloved by the Japanese public at large. It also fits in with the Book of Revelations that just as Satan seems on the verge of victory, he is stopped and abruptly struck down (as is the case with the final confrontation with Near). These ideas make this theory very tangible indeed - in fact, it's very possible that Ohba was intentionally using the Book of Revelations as a slight influence and running motif throughout the work.
 * Or perhaps L is Lucifer, incarnate on Earth to prevent Light from making him look bad? Light does have a fitting name and god complex, but he's brash and shows off far too much. Lucifer/Satan/The Devil works through a complex network of channels in nearly all modern depictions, preferring to stay behind the scenes unless necessary. He would never have killed Lind L. Tailor upon first sight, as such an action would call entirely too much attention to him and greatly compromise his security. Moreover, being from another realm, I'd think a fallen angel would have quite a few bizarre habits. The only question, then, is what happened to Old Lou after being beaten by a wannabe fanboy.
 * If Light's the Dragon, and Kira's the Beast, then who's the False Prophet?
 * The argument can also be made that Light passing on the Death Note and status of Kira to Mikami was symbolically identical to The Dragon raising the Beast from the sea and granting him domain of the world.
 * The moon isn't an evil spirit in Japanese tradition plus the moon isn't even evil in our society. This is a cultural thing that you've misinterpreted. The moon surname and Light first name represent his own inner struggle.
 * True, the moon has nothing to do with Light being the Antichrist. But he is saying that a kangi that reads "moon" is pronounced "Light" when it shouldn't be -- he's taking It Is Pronounced Tro PAY to extremes. He only appears to be Light, but really isn't; thus, he is deceitful, a false Light, and the Antichrist.

L is a body-snatching monster.
The Wammy's House's true purpose is to provide new bodies for L. The best and smartest of L's "heirs" becomes the body L will possess in case he dies. This explains why so many of Near's mannerisms are similar to L's: L just forced poor Near's original soul out and replaced him!
 * The only problem with this version is Near's markedly different investigation style from L.
 * No problem; there's nothing in the original WMG to suggest that the host bodies gathered at Wammy House aren't brilliant detectives in their own right; clearly, each time L body-hops he gains a portion of their abilities, maybe some mannerisms and some trace personality elements from the new host. This has the added benefit of making each regeneration a better detective than the last.
 * Heresy! The added mannerisms slightly decrease from L's later regenerations; no one is better than L. Ever.''
 * Near has the same dilated pupils as L, but only after he begins to pursue kira. Obviously these are some sort of Red Right Hand, indicating "L" is possesing the character. The reason L's pupil's contract as he dies, as opposed to dilating like a normal person, is that Monster!L is leaving his body.

L poisoned Light, making him less intelligent in the second half
Think about it. Light seems like he drops 40 points of IQ between the L and Near arcs, taking a bunch of stupid risks in the latter. Given how smart L is, he would know that, if Watari died, then it would prove Light was Kira, but then L wouldn't have time to implicate him. So, he developed an elaborate booby trap when the computer systems were installed, setting up the core computer systems that would most likely be taken by Light when he left to release poison gas over a long period of time. Given that Light would be working with the computers almost constantly, the poison would degrade his facilities of reason. By being non-lethal, L would avoid killing any innocent members of the anti-Kira group. The gradual dosage would prevent Light from noticing and minimize the effects on the other members. This also has a nice dramatic structure, since the second part can be seen as a two-part plan by L - reduce Light's intelligence considerably and then, when he's been sufficiently softened up, send in the two people most likely to be able to take him down.
 * Light made stupid mistakes before, such as the one mistake that told L that 'Kira' was in Japan to begin with, or killing the Federal agent when simply lying low would have sufficed.
 * Light also seems to drop several IQ points whenever it comes to Ethics.
 * Light is a lot smarter in the "second half" of the manga. They cut out a lot of his deductions in the anime (for example, when he understands simply from a couple of words that the president of the U.S is being blackmailed.) But he still makes a lot more mistakes than before. The L of the anime is a lot better with brain damaging poisons than the L of the manga.
 * Or he's just as smart, but making mistakes because he's slowly GOING FREAKIN INSANE.

L and his successors were "shields"
All of the cases they "solved" were solved by Ryuga Hideki. Furthermore, L using Ryuga Hideki's name was a failed attempt to get Kira to kill Ryuga. Ryuga had information about L that would lead to his demise, which is why L was protecting Ryuga rather then fulfilling his lifelong dream of building the world's largest sugar cube city.
 * And that was where L was in the second half of the series. Faked his death to run off and go complete that dream of his. Hey! Look out the window! I think I can just see a bit of a sugar white building being finished off in the distance.

L had a crush on Naomi Misora.
Because, c'mon, that hug at the end of the novel. Plus, a lot of his dialogue in the phone conversations seem like he's trying to impress her and is completely clueless to how annoying she finds him. After she kicks him and he finds out she has a boyfriend, the bad experience causes him to pretty much give up on relationships and become the basement-dwelling Covert Pervert we know today.

Yagami Light really is named Raito.
The letter "L" is hard to say in Japanese, for some reason. Light is Japanese. So, for once, maybe that crude Japanese approximation of his name is his actual name? Okay, that's way out there, but it's been theorized before.
 * Except that it's clear Soichiro speaks English, if not fluently, then at least very well. It's just that his and Light's Japanese voice actors weren't as good as the characters are supposed to be.

The Light Yagami who became Kira isn't the real Light Yagami
The real Light Yagami was a mild-mannered high school student, top of his class, who accidentally discovered the Death Note. He used it twice. After realizing that he had killed two people, he snapped, replacing his real personality with the one that would go on to become Kira. "1) Go hide in a corner for a couple of hours.
 * Also, the old Light Yagami would have become Gundam.
 * This is was made obvious when Light temporarily desnapped and became a morally upright young man. For a while.
 * Mja, surely a normal person's actions would be more among the lines of this:

2) Destroy the note book

3) ?????

4) PROFIT!

3) Live on the rest of their life in extreme guilt."

"1) Cry / dry heave in alleyway.
 * Even before Light was Kira, he was never normal. And if he destroyed that notebook, he would find an identical one a few days later. Death Notes regenerate. A couple of regenerated death notes later, he would definitely snap. We just saw the last cycle.
 * That makes for an amusing image- After several creative attempts at destroying it and some severe Sanity Slippage later... "Gah! Back again!!! * snaps, insane Kira laugh* ...Oh well might as well use it to become God."
 * What? No, they don't. The destruction of Death Notes occurs in the series itself.
 * Light's actions come pretty close to "normal" or at least what a "normal" protagonist would do in said situation:

2) Consider destroying the notebook.

3)	Rationalize actions, "I was doing the world a service, killing them" decides that if he's damned anyway for using the Notebook (remember he was prepared for some kind of punishment when Ryuk appears), he might as well take out as many bad guys as possible.

4) When no punishment is forthcoming... he's come too far to stop now, comes to believe own bullshit... I'M GOD!!! (Also have to keep the Shinigami entertained)"


 * That isn't Light Yagami. The Death Note he was given was in fact the ninth Millenia item from the Yu-Gi-Oh series that got lost and wound up in Death Note. After using it twice, the real Light realised that there was another presence in the book that was trying to possess him. He thought to get rid of it, however the dark presence from the Millenia Death Note heard this thought and decided to speed things up and possessed Light. This whole series, we only ever saw Yami Light - who was doing everything in accordance to...the APPLE'S plans! Yes, the apples secretly release a special chemical when consumed, which actually contains highly advanced nanobots that can alter an person's mind into communicating their plans of World Domination for them, they just need the perfect specimen to eat them enough to get the complete message, and this is where Ryuk comes in. So while he's controlling Yami Light on behalf of the apples, Yami Light is keeping the real Light surpassed in depths of his subconscious, allowing him to witness all the horrilbe things he's forcing him to do. So at the end,  it's really Light finally having enough with being controlled, and trying to get out to tell someone that he's being controlled, however Yami Light wasn't giving up so easily. Cue the breakdown.

L hallucinates everything after he sees the second Kira video
The case was real up to a certain point. Then he snaps, which is shown by his overreaction to the mention of 'shinigami' in the second Kira's video, because he hadn't gotten enough sleep.

Light is insane, and the whole series is a hallucination on his part
, so it can't be L's hallucination.
 * Of course, you could take into consideration several of the other WMGs here, giving reason to how he could have played out how the encounter would happen in his mind the entire time,

Light has a complete mental breakdown partly through the series.
Either, or. He's certainly under enough stress to have a breakdown. And the universe suddenly starts bending over backwards to bail him out. . Granted, it all eventually falls apart on him, but these things always do.
 * Light shifts out of reality right when

Light was controlling Penber's actions via Death Note on the train
So Raye Penber's kills count as kills for Light. "Raye Penber Heart attack "Passes in front of the "CAFEEL" coffee shop in Shinjuku station underground at 3:00 P.M. on December 27, 2003, carrying his laptop computer, and boards a train on the Yamanote line. Dies three seconds after getting off the train." (Vol. 2 pg 44 of the manga)"
 * This is even mentioned in the show / manga that he had written what would happen in the Note beforehand:

L has Asperger's Syndrome.
L is pretty much an Asperger's poster boy. He has poor social skills and no friends (he even admits that Light was his first friend ever); he is extremely intelligent; he can't seem to sit still without doing something with his hands (all that obsessive sugar-cube stacking); he has an otherworldly way of looking at things; and he doesn't seem to realize he's bothering people, Misa especially.
 * Although with Misa it doesn't count. Essentially everyone other than Light and Rem bothers Misa. Suppose you can add Light's family as exceptions too, but considering they're Light's family, she's just trying to get on their good sides to impress Light and hope for their consent to get with Light. Besides, she really saw L as a love rival, because Light was giving him nearly all his attention, and Misa wanted that attention on her.
 * This troper has Asperger's, and totally agrees with this theory.
 * Consider also how he shows a few other traits of it; first, there's a couple of scenes where he exhibits a few symptoms of pica (remember how he peeled a banana with his teeth?), or the way he just seems to be totally detached from others. When I say detached, look at how others react to him, and he really doesn't seem to mind that everyone considers him weird, if he even notices at all. Plus, there are moments when I act like a female version of L myself.

Everything that happened in the series was imagined by Light
The Death Note was made as a prank by a random student. When Light wrote the name of the first guy in, he was gunned down by police rather than having a heart attack. Light, disillusioned by the crime in the world, desperately wished to believe he could make a difference; the stress of being number one in everything rendered him unstable. As for the second guy, Light killed him himself using his sports skills and then ran off to avoid retribution; his mind made up a false memory of using the Note. The criminals that he wrote in the following week did not die, but he believed they did. He finally began to hallucinate Ryuk after a week of believing himself to be a murderer.

The investigation of the so-called Kira was imagined by Light and was his inner conscience protesting the killing of criminals. That side of him would be manifested as L, who is essentially exactly like Light in terms of intelligence and skill, but unwilling to conform to societal norms to represent the stress that came with being always perfect.

Misa was already a famous model before Light found the Note; Light only imagined having a relationship with her as part of his repressed sexuality. L, Light's subconscious "good" side, weakened as Light's "evil" side grew stronger and eventually died. Light was put into a coma as part of a failed suicide attempt when the police began suspecting him of killing the gang member.

At the end, when he is killed, it is his moral subconscious, resurrected as Near, rejecting the world he's constructed for himself. He is not sent into nothingness, but the world he lived in is. He spent those eight years in the coma and is now just waking up.

A number of different versions in the fine details of this theory are equally valid, so it is probably not 100% right.
 * Sounds like a better version of.

The entire series is young justice-driven Light-kun’s coma nightmare.
He's betrayed by people he thought were his friends and trusted- they tell him something fun is going down at this old abandoned warehouse. But it wasn't  (a figment of his imagination) that arranged things, but it was Sudou the Jerk Jock and his cronies come to give the poor nerdy high school student a beatdown and worse. He is rendered comatose, and in his dreams to counteract those feeling of powerlessness he dreams up a scenario where he’s given total control thanks to Shinigami powers and is a dark avenger of justice...
 * L is his conscience another facet of his own personality that recognizes that he has gone off track somewhere...
 * In his breakdown at the end of the series he begins to realize that this isn't real and not what really happened...

In the Movieverse, L was in love with F.
Which is why he writes his own name in the Death Note right after he finds out about F's death.

L is a werewolf
Okay. Where do I start?... He constantly sits oddly, in a style that looks like the way a dog sits on their haunches. He is shown with constantly dialated pupils. He has shaggy hair. He has naturally pure black hair. He constantly hunches over on himself, which could be reminicent of some interpretations of werewolves (gestalt form). He has an oral fixation. He looks more and more like he has issues the later on with his eyes. Look at when he's first introduced compaired to the chain incident. The issue is that he has more bags under his eyes later, and his eyes are shown wider and wider.

Now that I'm paying more attention, let me revise some. He also seems to not sweat (tennis mach, anyone?), he was only shown breathing heavily. This follows, considering actual wolves and dogs can only sweat on their paws. Considering he was in his usual outfit, while Light was in a t-shirt and shorts and he was sweating all over the place.
 * This would also explain why L doesn't freak out when he sees Rem. He is already a supposed fictional being, so the presence of a Shinigami doesn't come as much of a shock to him.
 * Except (and I'll poke a hole in my own theory) he freaked out at the mention of shinigami in the anime version. (His screaming while holding his hands up in the air thing.) In the manga, he just fell, so the anime version makes me laugh. Maybe he'd be a werewolf in the manga and not the anime?
 * So we've got Simon Yagami, Misa Renard, Aeonear, and now... Corn-L?
 * If L isn't entirely human, that opens a lot of questions about how the Death Note works on him. Maybe he can recover from death (although that would be more like a zombie).
 * A zombie werewolf?
 * Maybe he's an abomination a werewolf-vampire crossbreed. L is pale and doesn't like going outside. Maybe he's slightly adverse to sunlight.
 * Or maybe he sparkles.

L is a vampire.
See above. He's thin, pale, dislikes going outside preferring to be the Voice With an Internet Connection and is never seen eating "real food." It also explains why he's insanely wealthy-being immortal he could have saved up for centuries.

Light is a werewolf.

 * Werewolf Theme Naming: "Moon Night-God" anyone?
 * Whenever Light gets really angry he's suddenly sporting Expressive Hair and fangs (see when L pwns him right after the Entrance Ceremony, the last two episodes, and that deleted funeral scene... where he barks like dog at .) But Light being Light he has mastered his powers and Our Werewolves Are Different. (Also it is necessary since when he goes out walking at night the moon is always full.) That's why he's so good at hiding his true nature, he has learned to blend in with the sheep- he is able to keep a calm facade most of the time though he does have some serious rage issues-see his Villainous Breakdowns. ("Dammit, he got me! Rawr!")
 * It also explains his cavalier attitude to any punishment he may receive for using the notebook-he's already mastered one Curse he should be able to handle a simple notebook, right?
 * That's why Light has a perfect body and has amazing athletic prowess when it is implied he spends all his time studying and snacking on potato chips.
 * It's also why Light gets a

L deliberately manipulated Aizawa into leaving the Kira task force.
L suspected something was up when Light started vehemently proclaiming his innocence, and evidence in support of that claim came up at a convenient time. He deduced the possibility that Light had given up "Kira's power" and his memories of being Kira, as part of a Xanatos Gambit to prove his innocence and ultimately kill L. L knew he needed a backup in the event that he was killed, and when the third Kira's threats meant that the Japanese police would no longer support the task force, he saw his chance. Knowing that Aizawa was the one with the most to lose if he quit his job, and had been distrustful of L and disturbed by his methods for quite some time, he subtly pressed Aizawa into strongly considering whether he was willing to see the investigation through to the end, no matter what. When it became evident that he would, L covertly signalled to Watari to "innocently" remind L of the fund he had set up to support the families of the task force members in the event that they were coerced into leaving the police, bringing Aizawa to the conclusion that L had withheld the information to test his resolve, and resentful of such manipulation would leave the task force.

This would mean Aizawa, a competent investigator, would not be around Light for the months he was unable to remember that he was Kira. L deduced that if Light should kill him and take over the task force, that Aizawa would return to the task force (if he had not already), and thus the task force would include someone most inclined to consider the possibilty that Light was Kira, having not been around him during his temporary "innocence". This would provide L's successor with a clear insight to the workings of the task force, and a vital weapon to use against Light. L may even have left instructions for Near that Aizawa was the surest bet for defeating Kira.

Forget Light, L was the true mastermind, with an incredibly subtle Xanatos Gambit that transcended his own death and went Exactly as Planned.

High school super-genius Light Yagami is really Kira!
Think about it! From the very first transmission L ever made, we know that Kira is in Japan! And Light Yagami is one of the smartest students in all of Japan, more than capable of staying one step ahead of the detectives pursuing Kira! Also, his father works for the police, giving Light tons of access to sensitive information about the criminals he kills!
 * But he's such a nice guy! I mean, I've seen some crazy wild mass guesses but come on.
 * No, it makes sense! Clearly him working with the police force on this case is part of some manner of incredibly overly-complicated plot to throw off suspicion!
 * That's ridiculous. Next you'll be trying to tell me that Bruce Wayne is Batman!
 * That millionaire playboy? He's too busy partying and managing the affairs of the Wayne foundation!
 * Why does the above troper think Alfred is friends with Batman?
 * And Shinichi Kudo is Conan Edogawa!
 * What next, Clark Kent, Superman? Don't make me laugh, kid, Kira is that pesky kid that always spoils our team's plan! And Pikachu is his Shinigami!
 * But...Clark Kent wears glasses!
 * Guys, this is serious WMG. I don't want anymore of these crackpot theories about Light Yagami being Kira. Everyone knows that guy is way too busy flirting with girls and studying for College Entrance Exams! Obviously, there's just no way HE could be Kira.
 * No, its true. I have proof, and I'll be posting it on the inter
 * It seems here that the above troper died of a heart attack.
 * It's just as well, because I've got a different theory. Light is L. I mean, think about it, "Light", "L", right? Except, and here's the crazy part, I think there's actually more than one L. See, the first L died when Ligh
 * The above troper didn't die of a heart attack, but was actually abducted by Candle Jack was has been wor
 * Working with Kira this entire time. It all makes sense now. If Kira could not see your face due to you always having it covered (handy if you're a female coming from a society that doesn't allow you to show ANY part of your body) Candie Jack can not only kidnap you if you say his name, but will kidnap anyone who attempts to say Kira's real name, because all Candie Jack needs is for you to say either name for him to kidnap you. It's Fridge Brilliance!

L becomes aware of his fictionality.
The reason L freaks out when he admits the existence of Shinigami is that in his mind, he comes up with an abstruse proof of the impossibility of Shinigami and the natural conclusion that he is a fictional character in a fictional universe. Despite his mental fortitude and natural intelligence, there's only so much a sleep-deprived youth can take.

L was not actually murdered; he died of natural causes
Rem kills Watari via death note, then dies immediately thereafter. The only reason L dies is because of a NATURAL heart attack brought about by his incredibly poor nutrition. The timing of his death is merely coincidence. Thus, Kira did not actually defeat L.
 * This assumes that Kira didn't have this in mind and therefore subtly manipulate L into eating more and more candy in place of actual food while they were chained together, wearing him down to the point where he dies of malnutrition.

Light died exactly when he was supposed to according to his number, & went just as planned... by fate.
Think about it - Misa was set to die on Year X, Day X, Hour X, Minute X, Second X. By a murderer. And this was the end of her life as predetermined by her number. This death wasn't because of a disease, accident, old age, or anything else - it was a death caused by another sentient being; therefore, the entire idea of "free will" in the Death Note world is a load of bunk, and everyone except the Shinigami are subject to a law of fate and predetermination! Ryuk even said that he knew when Light was going to die, and with some glee at that; combine this with the fact that he said he would be the one to right Light's name in the Death Note when things got boring for him. While this seems like just a threat on Ryuk's part, perhaps Ryuk forsaw Light's death entirely beforehand, and therefore knew that Light would die exactly when he did, and by Ryuk's hands - it wasn't a threat, it was a prophetic message which couldn't be avoided by a human. Taking this into account, then, everything Light did, L did, Near, Misa, and everyone else did was predetermined from the moment that Light picked up the Death Note. Perhaps Light's death number was different before taking the Death Note, but thanks to Ryuk's meddling (because, as was stated before, the Shinigami are outside the realm of fate - or those that do not interfere in human affairs, at least), and dropping of the Note, Light's number was changed to reflect the exact moment Ryuk wrote his name in the notebook.

L is Shinichi Kudo
You know it's true. Shinichi after turning 10 and starting a new life under the name Conan Edogawa, never managed to go back to his old self, and just grew up as Conan, later becoming L.

Light is adopted.

 * ...He looks nothing like the rest of his family.
 * Actually, that would explain a lot... So  is Light's father?
 * Wait... Luke means Light in bastardized Latin. Luke Skywalker. Light Yagami (Night God). Holy crap!
 * Light is adopted and he has a brother or two...
 * It makes sense-he's the Odd Name Out. You've got Souichiro, Sachiko, Sayu... and Light.
 * Also Souichiro does seem to favor Sayu at point (specifically the scene in the hospital where Souichiro can claim to L that he is only sure that SAYU not LIGHT wasn't Kira) and, not to mention, Light could do anything with how smart he is, perhaps he wants to be greater than his (adoptive) Dad because he wants to be seen as worthy.
 * This leads to his OCD, perfectionism and eventual god complex when he gets the Death Note.

Light was adopted...from the Wammy's House.

 * Discuss.
 * And Light really was L's "first ever friend."

Light was adopted from Wammy's House and he has a brother... Matt.
Clothes and Fanon hair-dye aside they look very similar.
 * Count on Cousin Gevanni as well.

Light is A from Wammy's House.
Maybe A as in Asahi. He's a genius and he's about the right age. That means he survived his suicide attempt but he had such severe mental trauma that he somehow got Easy Amnesia from it. So L or Wammy adopted him out to a nice normal family far, far away on the other side of the planet in an attempt to Give Him a Normal Life without any stress... and holy shit did it go wrong...
 * That's why Light is so creeped out upon meeting L! It's not just because L looks creepy but also because Light has Repressed Memories involving Beyond Birthday... (the jam... GET IT OFF!!! Sorry, what were you saying?)

If Light was adopted then "Light Yagami" isn't his real name.
You see thanks to spending time with L and being forced into chronic sleep deprivation he's developed narcolepsy or something.

Light is a Bastard Bastard.
Soichiro isn't Light's biological father. It would explain why Light looks nothing like him in an anime, why Soichiro seems to favor Sayu, and why Light and his father seem to have somewhat strained relationship even before Light comes under suspicion of being Kira.

Following above guesses Light would have become a killer anyway even if he hadn't picked up the notebook because he is host to a Dark Passenger.
Light Yagami looks nothing like the rest of his family with his (red-)brown hair but he does kind of look like Dexter. They could be (half-)brothers. Dexter,  and Light could share the same vicious bastard of a biological father. The mother was a Japanese woman and, after Light was concieved, she returned to Japan and either dies after giving birh or abandons the child and, like Dexter, Light is adopted by a police officer but that's where the similarities end. Light is very much "an unchecked version" because unlike Dexter who had Harry and the Code, Light was raised so sheltered and made to adhere to such strict morals that he can't cope with the very idea of evil in the world or himself in any terms other than Kill It With Fire!!!!!111 (or rather heart attacks). However since Light didn't have the same trigger as Dexter  it took some extra encouragement to trigger his Dark Passanger. Notably when Light  he lacks the same evil and cunning that he has when he uses it. Something similar happens to Dexter when he, for a time  in the Dexter book series.
 * That would be an interesting family reunion: they'd be all affable in their charming personas (and they could trade fashion tips on those awesome shirts: Hawaiian vs. the male model catalogue) and then try to kill each other when they figure out their true colors. Light would probably run rings around Dexter as the Chessmaster but on the whole he is a Non Action Big Bad and Dexter would more than likely win in any physical confrontation.

L is also a host to a Dark Passenger.
L is known to have a Dark And Troubled Mysterious Past so maybe Wammy found L early enough that he could prevent him from becoming a Serial Killer and trained him to control his urges to become a detective instead, and L's many weird quirks are manifestations of his suppressed violent urges. Maybe that's what Wammy's house does: Mello and Near also have some sociopathic tendencies and B could be a less then successful outcome of that program. Like Dexter and Doakes Light and L share an almost psychic connection often thinking the exact same thing, like their Passengers are communicating with each other.

Dexter is an AU counterpart of Light Yagami.
They're both serial killers who kill killers.
 * Addendum: Their standards are very different. Light kills to create what he would consider the perfect world, and he thinks of himself as the incarnation of justice. Dexter's only reason is his urge, and he is far from being proud of it. Dexter EXPLICITLY limits his targets to those who have committed murder. Light's target are not only murderers, but also petty criminals and eventually everyone he considers a "burden to society". Light is pride and presumption incarnate; Dexter probably isn't.
 * Also, Dexter generally rules out killing people who served their sentences. Light kills dozens of people already behind bars.
 * Dexter most certainly isn't, when anyone tries to give him some kind of Not So Different speech or anything of the sort he simply agrees. He even tells Miguel "You're all just unchecked versions of myself. The only difference is I know I'm a monster." (Paraphrased)
 * While Light and Dexter share many similarities (both are Serial Killer Killers that come from police families, have a Morality Pet sister, a traumatized Beard girlfriend/wife, and are very good at hiding their gruesome hobbies Dexter is almost an anti-Light:
 * Light thinks he's a God, Dexter thinks he's a monster.
 * Light becomes a monster because he was such a Wide Eyed Idealist to begin with. Dexter is more cynical and finds youthful idealism dangerous.
 * Dexter believes the world would probably be better off without him (not that he's in any hurry to make the world "better off"). Light thinks he's doing the world a favor and feels entitled to rule it.
 * Dexter is a killer in the traditional sense-he gets intimate with his targets and carves them up. Light is a Non Action Guy (and considering all that happens in the series, it wouldn't be surprising if he even had a phobia of guns and violence like Dex has an ironic phobia of blood.) Light commits mass murderer using magical means—he kills from the comfort of his room by writing names in a notebook. There is no sense of immediacy, no blood, no struggle. His targets are dehumanized and the act of taking so many lives would likely have all the psychological impact of a kid playing video games—look, I killed over 10,000 evil Mooks—aren't I grand?
 * Dexter sees killing as playtime, Light claims it's a great burden / sacrifice on his part (though, like Dexter he seems to get an almost sexual enjoyment out of killing.)
 * Light likes to plan out his next move 20 steps ahead and while Dexter carefully plans out his kills he tends to do things more on the fly.
 * Dexter is very witty in his Inner Monologues, Light doesn't have much of a sense of humor.

Light has a cousin named Ichigo
Because how many auburn-haired Japanese families do you know? (Only like in every anime...)

Some more of Light's relatives train digital monsters.
Tai and Hikari Yagami. And they both have brown hair...
 * Maybe Hikari is the reincarnation of Light? They're both messiah type characters, with strong ideas of what's right and wrong. And what exactly is Hikari's crest? Why, it's the Crest of Light! Like Light, she's got some weird connection to darkness, despite them being good-light-people - With Light it's the Death Note, with Hikari, it's the Dark Ocean/Sea of Darkness. Of course, they're different in the way that while Hikari has a case of Big Brother Worship, Light (obviously) does not. (Though, Sayu does, but maybe not to the same extent.) Heh. So, how long before Hikari becomes the new Digimon Kaiser/Emperor/God of the Digital World, believing that, "This digital world is rotten, and those who are making it rot deserve to be deleted!" ... Or maybe they are relatives, and Light has found a worthy successor to Kira's legacy in Hikari? Either way, it's probably not going to make Light very happy to find out that there's a second world he's going to have to cleanse. Poor, poor, Light.

Light is Ryuk's son
Ryuk impregnated Sachiko Yagami, and Light is half-Shinigami. Ryuk didn't drop the DN randomly, he wanted Light to follow in Dad's footsteps.
 * He has his father's eyes...
 * ...following this soap opera revelation, Beyond is his half-brother from Ryuk getting it on with L's mother.

No, Aizen is Light's biological father.
Just as planned. 
 * Aizen can even be seen in the first episode of the anime disguised as Light's English teacher.

Light's physiology is subtly different to a normal human's.
Okay, tring to explain this. At one point, Light eats a scrap of deathnote to dispose of evidence. Deathnotes are made of a substance not found on earth. Normally, an organism's tolerance to a substance is roughly proportional to its occurence where the organism evolved. (Which is why we're rather dependent on some common substances such as water, and sickened by many rarer ones, like radium.)
 * This observation and theory lends support to the "Death Note owners become Shinigami inhabiting human bodies" and / or "Light is Ryuk's Son" theories.
 * Maybe they skipped the part where Light had to be rushed to the hospital to get his stomach pumped. Because if it's not toxic one could make use of the unlimited pages to survive when stranded in the wilderness or cure world hunger or something...
 * Just because something isn't toxic doesn't mean it's food. People can eat regular paper with no ill effects, but they'll still waste away and die if they're not getting proper nutrients, even if their stomachs are full of delicious notebooks.

Light was Dead All Along.
He was dead from the moment he picked up the notebook, he just never noticed (nor did anyone else.) That would explain his Lack of Empathy and apparent lack of sex drive. As to why it affected Light in this way and not the other Kiras well, he had the dull eyed look even before he picked it up. As stated in an above tin-foil hat theory maybe Light is part-Shinigami.

L isn't outsmarting his food...
He's bulimic. You can't just wish your food away. The amount of food he eats is easily comparable to a binge, yet he's impossibly skinny. It could start easily too: a very young L is stressed out on a case, has no healthy coping mechanism (you can't tell me he would've), eats too much, feels too sick to focus, so sticks his finger down his throat so he can focus on the case instead of his stomachache. Repeat ad infinitum. He cottons on to this, of course, but by this time he's well and truly entrenched and he refuses to go to therapy because that would require trusting people. He might have fought it, but then came the Kira case with way too much stress for him to deal with without the food-based coping mechanism. (When he and Light are chained together, he positions them within chain's length of the bathroom, waits for Light to fall asleep, and then makes himself throw up. If anyone could keep an eye on someone while intentionally making themselves ill, it would be him.)
 * Now THAT would make for some angsty fan fic.
 * It's been done.
 * If done well, I demand links.
 * 
 * Still, HTR 13 has a comprehensive list of everything that we've ever seen enter L's stomach. His tendency is to have the sweet in front of him, take a bite or two of it, and promptly forget about it in favor of talking. If anyone's bulimic, it's Mello. He's got the personality for it.
 * To an extent he may be able to "wish it away" through a superhuman level of control over his bodily functions via thoughts much like monks who can alter their body temperature through meditation.
 * He may also use drugs to boost his metabolism or laxatives to rush food through his system before he can fully digest it.
 * No wonder he is so skinny and has no muscle.
 * Also might explain why he is incapable of sitting like a normal human being.

Light's Not Quite Dead
You see, after he went to Mu, the Shinigami became scared that he'd gain dominion over the Nothing After and use its power (or a well-placed Cosmic Horror) to get revenge on reality, so they made him corporeal and sent him to the alternate timeline of the Code Geass series. Light drops out of the sky and crash lands in the cart, as seen during Code Geass' credits. Lelouch and Light have a Magnificent Bastard Chessmaster contest which results in a tie, causing both to agree to join forces to take over the world. And it was awesome. And FABULOUS once Suzaku joined the party.

Light apparently became less intelligent because he was over-exerting his brain.
This is related to the poison gas theory above. What if the brain-power required to maintain all those Xanatos Gambits, as well as his good grades, was just beyond him, so that he ended up repeatedly straining his brain? The damage from this could have sped up the 'natural decline' in his intelligence.
 * Intelligence does not work that way. Emotional stress, however, does. Especially if said emotions go ignored and unvented for five years straight.
 * So, if only Misa has been a little (lot?) more determinated to get laid with Light, we would have had a different ending? I mean, Light considers masturbation as a waste of time - he buys pornography just in case someone put espionage cams in his room, and shows no interest in the several women that would jump to his bone. He failed his plan because needed to... ehm... relax a little?
 * There is also a theory that those who relinquish and regain a death note suffer psychological/neurological damage from losing and regaining their memories of the note. This would explain why Light seems to become less intelligent. And of course, Misa has lost her memory of the note not once, but twice.

L survived
This might be an anime-only thing, but...

Normally when a person dies, his/her pupils dilate. L's pupils, however, contract. Unless they were going for a Psycho homage, I can't see this as anything other than a major neon sign pointing out the fact that he's a big ol' faker (if it's just a case of Did Not Do the Research, why did they make such a point of focusing on those shiny grey irises?).
 * Might be tough considering his pulse was checked by at least two task force members and HE WAS BURIED.
 * There are plenty of drugs that when injested can simulate a stopped heart. It's not like anyone's going to be clamouring for an autopsy on an obvious Kira victim. And we don't know that he was buried; we know that a coffin with something around his weight inside it was buried.
 * The coffin was probably filled with all those vegetables L kept hiding under his bed to avoid being forced to eat "healthier". What better way to dispose of unwanted greens?
 * Which is why I have a theory about L and the fact that he really didn't die. I seriously don't think he died, now that I really consider things.

Columbo is L's Maternal Grandfather
Traits they share: Limited Wardrobe, mysterious backgrounds, Hyper Awareness, And Another Thing ... they're both detectives. Since Lamarck Was Right all of this implies that L and Columbo are related. Since Lawliet isn't an Italian name, Columbo's daughter must have married a non-Italian. This, of course, begs for the prequel story in which L learns from the master.
 * Columbo also suggested L's name after the initialism of their esteemed ancestor Linnaeus.
 * To further back up your theory, Word of God has admitted Italian in L's heritage.

During the Potato Chip sequence, Light choked to death.
The rest of the series was a hallucination that occurred in the seconds before his death. He started acting crazy at the end of the series because his brain had lost too much oxygen flow and was starting to lose coherency. His heart attack was how he perceived his own death. He wouldn't accept that he had been taken down by a snack food.
 * I love you.

Light is also a fan of Hideki Ryuuga the pop star.
He dresses like him and uses the same cheesy romantic quotes when trying to impress Takada.

L is Raito's reincarnation!
Maybe Raito, when taken to "Nothingness", tried to find a way out, and he was given a way out? The only way for him to go to heaven or hell was - to stop himself in his madness. It'll explain all of the Gambit Pileups that were made in the first half. Also, this will explain, why L wasn't really satisfied with his results. And why he still suspiced Raito, even if he couldn't be the murderer. And why he predicted every Raito's move (remember those "fights", that they had?) Think about it.
 * ...that would add a disturbing new element to the Slash Fic.
 * So is he just a Raito in purgatory?
 * This may or not be related but on top of the having the same thoughts / thought patterns, Lawliet would actually be pronounced Low-Light (or Ro-Raito when written in Japanese).

L became a shinigami after he died
Let me try to explain this in the least confusing way possible. First of all, let's say lifespan is like energy. It cannot be created or destroyed, only transfered between people or changed to another form. When a human's name is written in a Death Note, all of their lifespan is transfered to the writer and changed to form that only those who have already died can use. This is why shinigami gain lifespan when they write a human's name in a Death Note and other humans don't, at least at first. They gain lifespan only usable in the afterlife, so when the Death Note user dies, he becomes a shinigami when the hidden lifespan becomes active. This is why the shinigami possessing the human is obligated to kill said human before they die, to steal their current and hidden lifespan, preventing them from becoming a shinigami to avoid the possibility of an over population of shinigami.

Now, when Rem killed L with her Death Note, she didn't gain his lifespan because she had already died from killing Watari. L's lifespan didn't have anywhere to go, and had already been transformed by Rem's Note so it stayed with him and became usable to him as a shinigami. However, even after becoming a shinigami, he couldn't kill Light due to rule XXXIV. And, in the anime, when Light was finally defeated by Mello and Near and dies, [http:http://www.youtube.com/watch?v=8cy_hXhMKwI&feature=related L goes down to witness Light's death], his reasons for doing so are debatable.

At one time, L had possession of a Death Note
He couldn't control his curiosity and killed one or two people to test the note out. Unlike Light, however, his conscience got the better of him. Filled with horror at what he had done, he renounced ownership of the note and lost all of his memories. His strange eyes, diet of sweets, bizarre habits and overwhelming fear of Shinigami are the reactions of his Lizard brain to the stress of the murders he committed. His memories of the note are gone, but his desensitization remains, which is why he's willing to take extreme measures to get the job done.
 * Why would L have a lizard brain?
 * http://www.crystalinks.com/reptilianbrain.html
 * Hmm. Remember the first few episodes where the police aren't even sure if the deaths of criminals are murders or not? L is sure - and this would explain why. He has no memories of using the deathnote, but his subconscious mind has vague wisps of memories regarding its powers. So he's positive that someone is killing criminals - even if he doesn't have all the concrete details/evidence.

The Death Notes are intelligent
They're not "of this world" because they're a bizarre kind of organism (like a Shinigami maybe). The shinigami's pens have a special interface with the organism. The notes are actually intelligent, and are the real gods.
 * But our pens work just fine on them.

L has mysophobia
In other words, he's afraid of germs. Am I really the first one to think this? The way he holds things alone is a very big clue that leads to this: It's always with as little actual contact with the surface as possible. He keeps his feet on chairs because they tend to be cleaner than floors. He doesn't wear shoes because feet sweat a lot more like that, feeling very germy. His lack of social skills is a manifestation of his inability to get close to people for fear of what germs they carry.
 * That doesn't make much sense. L doesn't wash himself very much, chews his nail, the idea of being chained doesn't gross him out.... Can someone be afraid of germs but not at all keen on hygiene?
 * Howard Hughes, anyone?

L's unique way of holding things is to avoid leaving his fingerprints and other evidence lying around because that could lead to his enemies discovering his identity.

 * Then why does he hold everything by the tips of his fingers? It would be more likely for him to be deliberately leaving his fingerprints everywhere as a sign to prove he was actually there.

L is an ex-smoker.
Bear with me here. The gigantic amounts of candy are a subsitute for cigarettes. The original plan was to cut down on candy after a while. It didn't go so well.

Combine this with the bulimia guess above, and you can get some...interesting fanfic.

"Lind L. Tailor" is the real L
Of course, Lind L. Tailor isn't his real name. The man we think of as L,, was L's bumbling sidekick. "Lind" was so brilliant a detective he had completely deduced everything about Kira, from how he kills, to the existance of Shinigama, to the fact he is Light Yagami. Had he not died, he would have explained all this. Unfortunately, he happened to die of an aortic embolism exactly forty seconds after Light wrote his name in the Death Note. Panicking, his sidekick took over, making up a crazy story about "Lind" being a convict. Everything "L" discovers up until his own death is actually taken from some notes "Lind" wrote on the case, which were regrettably incomplete.

L is a collector of the world's greatest criminal masterminds.
That's why he only takes on cases he's personally interested in and it is straight out stated that he's shielding Aiber and Wedy from prosecution since they are useful to him. Hence why approaching Kira with the expectation that he would confess all if he gets to know him well enough and would want to work for him makes perfect sense. Why wouldn't he want the honor of becoming part of his collection?
 * Two more Kiras and you'll have the whole set!

Light isn't actually that bright.
Oh, more clever than most people, and definitely than much of the task force, certainly. But throughout the series, his entire career is built on a series of one mistake after the next, many of which are caused by his egotistical pride, beginning with


 * An important fact to remember- Light is 17 at the start of the series (and he doesn't mature all that much (or at all) in the next five years considering he already thinks he's perfect.) Impulsiveness and poor decision making kind of goes with the territory... (there's a reason he's red to L's blue) remember that's what got him into this mess in the first place (Word of God: one has to be "foolish in order to use the death note"). He's a brilliant (and flawed) 17 year old kid with a God Complex... it's impressive he managed as well as he did...
 * Says it all really.
 * More food for thought- sometimes the most scatterbrained, disorganized, paranoid WRECKS of people make the best planners because they're over-compensating in order to just function... everything is neat and in its place, and every eventuality and contingency is thought up, over-analyzed, scheduled, and accounted for...

L is a Luthor.
His full name is actually Lawliet Luthor. In Smallville, at least, Lionel has fathered quite a few children other than Lex and put them up for adoption, it's quite possible that L was one of them, and was taken to Whammy's House. His incredible intelligence and obsession with defeating his opponent are pretty common among Luthors, after all.

Light becoming a shinigami is actually a punishment
So he's a shinigami now, he can take over the world as Kira. But then the his empire will crumble as they always. He'll probably try again. And again. Until he becomes bored as well.

L's real name was Elle.
He was too embarrassed as a child, so he got a name change to something cool-sounding. The reason the Death Note takes it as his "real name"? It was close enough.

L's real name is El.
El Mariachi  to kick ass.
 * Oh my god, yes!

Light reincarnated as the wolf Kiba from Wolfs Rain.
The Actor Rule, and he "can't go to Heaven or Hell..."

L has an enourmous tapeworm in his stomach

 * Which is why he can eat so much unhealthy and calorie-loaded stuff while still having an (almost) unhealthy low weight.

Light is an incarnation Randall Flagg.
The good man, the dark man, the man in black... Also, that means he's  He has many names in many worlds...

Light is Friend.
The virus is really a bluff, and what else is that the Book of Prophecy is a Death Note in disguised.

L is tripping on acid.
Seriously! The dilated pupils, the sugar cubes...

L sits that way because he has nerve damage from sitting and working too long.
There is an actual condition where it becomes painful to sit normally.

Light looked up to L as a kid.
Assume the following statement is true: Light wants to be a detective when he grows up. So his chief role models would be Daddy and, since Light always shoots to be the best, L who would just be gaining prominence as the World's Greatest Detective when Light was old enough to think about such things. This adds another layer to Light's extreme reaction during the Lind L. Tailor incident- Its Personal he was just rejected by his idol and "If I Can't Have You..."
 * I always thought that L kind of saw Light as a little brother...of sorts.

Light and L were sleeping together.
No wait, hear me out! That chain isn't nearly long enough for them to have separate beds! Of course L being an insomniac they wouldn't sleep together very well...
 * That's What She Said.

L considered the possiblity that Light is able to read minds.
He started considering it when Light began saying exactly what he was thinking, which is why even though he actually thought, he would still use those percentages in his inner monologues.

During the Yotsuba arc L and Light wore custom-designed velcro shirts that they could put on or take off without undoing the handcuffs.
Otherwise it defeats the pretense er... purpose of keeping Light chained 24/7.

Light is a member of the Assassin's Creed Brotherhood.

 * Well he's got the white hoodie for one...

Whether or not Light becomes a Shinigami, he'll take over the afterlife.
Come on. He got bored with everyday life; he'd get even more bored with nothingness/the Shinigami realm. Cue Xanatossing! He then fishes L out (possibly Near, Mello and Matt too) because he needs allies to take on the Shinigami, and they agree because anything would top The Nothing After Death. They then all band together to create a proper afterlife, with a new Heaven and a Hell and a Purgatory, and run their Xanatos Gambits against each other to determine who ends up where. Eventually, all the geniuses do in fact collaborate to create their perfect world, and balance it out. (They've got eternity to get it right, after all.)

This exists because it's not impossible per se and because I'm an idealist, and want to have some kind of redemption or happy ending for these people somehow. Besides, Rule of Cool and (if we have one) Rule of Heartwarming - just picture the reconciliation with his father, the crossovers, the peace they could reach, the other solutions boredom could take... plus an eternity of five-way Xanatos EVERYTHING. How is that not awesome?
 * Seconded... Like A Badass Out of Mu / The Shinigami Realm!
 * Heh, well, there's this alternate ending... Light can see the silver-lining in even a And I Must Scream situation.

L Did touch Misa's butt.
Angry L Fangirls in five...

L faked his death
He struck a deal with Rem. Rem was already fed up with Light Yagami, and L suspected the whole "13 days" rule was a load of bull. So he discussed a plan with her wherein he could fake his and Watari's deaths to fool Kira. So, he decided to either A)have Rem write his name in the Death Note so that he'd have a non-fatal heart attack and die in 10-20 years, or B)take drugs allowing him to slow his heart rate almost to nothing, thereby appearing to be dead. He'd go into hiding, and let his successors catch Kira as a test.

L's identity was kept hidden even pre-series because...
He's the last surviving orphan of a family coming from Innsmouth, Massachusetts. He has the look—the bulging eyes, white-grey skin, his hunched over walk and occasional Primal Stance which means he’s not completely human so

L is a wizard and he spent some time in Azkaban.
While he was still attending school at Hogwarts he was sent away for a crime he didn't commit. He managed to escape and clear his name however the corrupt bureaucrats stripped him of most of his magic and memories afterwards. L is later found by Quillsh Wammy who takes him in and trains him to be the Great Detective L. Though L has gaps in his memory he does remember how a Miscarriage of Justice screwed him over and he hates injustice with a passion. He has enough magic left to Detect Evil and knows immediately that Light is Kira.

Light Yagami has the powers of Haruhi Suzumiya
Like Haruhi, Light is unaware of his powers. Wishing for a way to cleanse the world of scum and villainy, he subconsciously created the Death Note, as well as Shinigamis.

L became Ulquiorra.
Just look at them side by side. I rest my case.

Light is a descendant of Miyako Toudaiji.
Most of her life, Miyako appears to be an Amateur Sleuth who wants to make the world a better place. However, the thing is she's distant to almost everyone except Maron. She secretly despises of what the world has become: rotten. Her world is already perfect, if it wasn't for the demons that Jeanne fought against keeps on ruining it. The most likely evidence of this is when. Somehow,, there is still remnants of it to infect the Yagami bloodline. This is why Light has become the Villain Protagonist that he is. He has somehow manages to control the urges of until he found the Death Note, giving into to these urges.

L is an abuse victim.
Yeah, this idea has been done... A LOT but it would explain a lot of L's behaviors: The Aloner, Extreme Doormat who Hates Being Touched and considers no one to be a friend. It also explains why L thinks of himself as a monster-not only because he must deal with the moral greyness that comes with his profession but because he has internalized the abuse. This also explains why he would want to bury his Dark and Troubled Mysterious Past even before meeting Kira.
 * Before meeting Watari L was abused by his parents or guardians who loathed the "ugly child" and was terrified by how smart he was. Watari rescues him and takes him in at Wammy's House where L receives Training From Hell to become the World’s Greatest Detective. But as grueling as the competition got with the other contenders for the title he was happy there-he had found a place where he was safe and he could use his massive intellect in a productive way. Watari rewards L's good behavior with sweets and it's something L never grows out of.
 * Then just as L is adjusting to his new life along comes "Mr. Aggressive Top" Beyond Birthday who must surpass L in every way. You wonder why the guy has trust issues.

Before finding the notebook Light was suicidally depressed.
Yeah, this one's been done too, but it fits. Suicidal people sometimes resemble really bored people and he might have felt alienated being so scary smart he can't really relate to the people around him. Light sees the world around him as "rotten" and for all his genius he feels useless to fix it and doesn't really perk up until after he's found what he thinks is his "purpose." It also explains why he's so drawn to the Death Note, his fascination with Shinigami, and then why he keeps risking more and more-it's out of a subconscious deathwish. The only other time he seems truly happy is during the Yotsuba arc when he's  because then he also has a purpose-  and since he   he isn't lonely and bored anymore.

After the events of the series Light moved to Castlevania.
See here:. He took Misa along with him. And then Near, upon discovering that Kira, follows them, wearing glasses as a clever disguise.

Light was actually raised in
Light is an evil genius just like  thus it would be no surprise to me if they both knew each other at an early age. However,  than Light.

L is a descendant of Detective Meguro.
Let's see the results. Highly eccentric detective? Check. Obsessed of finding his target? Check. Being a genius? Check. Constantly making some gestures? Check.

L will grow up to be Inspector Runge.
They are both highly eccentric detectives, both quickly become obsessed with finding their target (L with Kira, Runge with Dr. Tenma), both are (In Runge's case, supposedly) at the top of their field, both are basically geniuses, L is constantly doing something with his hands while Runge is doing the typing thing.
 * Except Monster takes place way before Death Note. So unless L preformed time travel, probably not.
 * Or unless he's a Time Lord. But that's a whole other page...
 * AND he's learned how to be a great detective without sacrificing his posture.
 * These things are not supposed to make sense. It's actually the serious guesses that are missing the point.
 * Alternatively, L is Runge's illegitimate child.
 * Wouldn't Runge's unnamed grandson be about L's age by the time the events of Death Note come about?
 * No, L's 25. The grandson would be about 12. If anything, the grandson is Near.
 * It's just that Inspector Runge and L both have the anime version of Asperger's Syndrome.

Ryuk lied about Mu,Light and L got reincarnated(perhaps backwards) as Watson and Sherlock Homes respectively

 * But wouldn't Light be Moriarty?
 * Maybe B is Moriarty?
 * Let me explain,people are always saying that if things had been different they could have been friends.So this time they are,their Tragic Bromance has a happy ending,fans of them as a platonic friends and Yaoi Fangirls alike go home happy.Everyone wins and Watari is Mycroft and Naomi is Irene Adler.

L has diabetes.
Come on you can't eat that much sugar without consequence! That would also explain why L doesn't wear socks-because he doesn't want to restrict the blood flow to his feet.

L is Batman.
Watari is Alfred, Mr. Yagami is Comissioner Gordon, The pink angel crepe van is the batmobile, Near is Robin, Mello is Azrael, Wedy is Catwoman, Aiber is the Penguin, Misa is Harley Quinn, Rem is Poison Ivy, Beyond is the Riddler, Ryuk is the Joker and Light/Kira is Ra's Al Ghul, Mikami is Harvey Dent/Two-Face?

Death Note: Another Note was Mello's suicide letter
Mello knew, and even planned, to die after kidnapping Takada. He fabricated the entire story as a way to reflect on his own life. Look:


 * Both Mello and BB admired L (to a certain point).
 * They were both runner ups.
 * They both grew up at Wammy's House.
 * They both tried to hurt the person ranked above them.
 * They both wound up at Los Angeles after being at Wammy's.
 * BB planned to kill himself with fire, but didn't get the chance to. Mello almost died at the fire at Los Angeles, but survived.
 * They were both eventually killed by a death note.
 * They both had sidekicks that were mentioned briefly and eventually died. (A and Matt)
 * OBJECTION! Mello couldn't have fabricated that story! L himself mentioned the case by name when he found out that Naomi Misora went missing!

L had Mello learn about the events of Another Note in an attempt to Scare Him Straight.
L was probably trying to teach him "See, this is what happens if you take your rivalry too far." Though it seems to have backfired as it sounds like Mello found Beyond to be Unintentionally Sympathetic.

Mello is a FTM transsexual
It makes sense, sort of. When Mello is introduced, his clothes and body are androgynous. Then he leaves, saying he will live "his own way," far from everyone he used to live with. Next time we see him, he dresses and talks masculine, but he still has feminine features. His figure leaves room for doubt (is he just well muscled, or are those bound breasts?). Then he gradually becomes more masculine just a few years too late to chalk it up to puberty (he can't be that late a bloomer). He also keeps his gun in the front of his pants, which is easier to do without a penis, and lacks a bulge in the area even though his pants are so tight that it's a wonder he can still sit. And transsexuals are cool.
 * A bar of chocolate says Matt is his ex-boyfriend.
 * Certainly not "ex". Given that everyone is gay or bi, certainly not straight, it's much more likely that they hooked up, or at least didn't break up, when Mello transitioned.
 * This isn't within Death Note itself, but Madonna played Mello convincingly in her "Jump" music video.

The confusion over Mello's gender was either planned, or the creator wasn't sure what he wanted Mello to be.
In the manga, Mello isn't referred to by any gender pronoun for quite some time. Besides one of the gang members, who I'm convinced had a massive unrequited crush on Mello, Mello isn't shown attracted to anyone or in a romantic situation for a long time. Some might say he never is. Granted that simply puts him in the same class as many other characters, but if the creator wasn't sure if Mello was a boy or girl, it makes sense not to give him any sort of love interest. It also makes sense not to do so if the plan was to make people wonder. Since Rem seems to be the only character with openly homosexual feelings, seems to be because there are people have argued that her love for Misa is platonic, maybe the creator assumed everyone would consider Mello heterosexual, and therefore, his love interest would give away his gender.
 * A similar argument could be made for Near.
 * I'm sorry, but you lost me. Which of the arguments could be made for Near? If I recall correctly, he was established as a boy early on. So, am I wrong, or are you talking about a different argument?
 * Well first you have Cross Dressing Voices - Near is voiced by a woman in both the original and the dub. Also with the way he's drawn he could be mistaken for a young girl.
 * Jossed. In Book 13, Obata explicitly states that he intended to make Mello masculine, and Near androgynous, from their first scene. One of the few moments where Obata seems to have weirdly misinterpreted how people would see the characters. Also, the plan was to have reversed the character designs (where the short, "effeminate" one would be Mello, and the taller one with straight hair would be Near), and was changed at the last minute.

Mello is a girl.
S/he's crossedressing because s/he feels that s/he wouldn't be taken seriously as a girl. If you think about it, it explains a lot.
 * Or, alternately, s/he just doesn't want any of her/his mob partners to get any... ideas. Or it was L's idea, for whatever reason. Mello certainly adored L...

Maki of L: Change The World grows up to be Mello.
Think about it, it makes sense if. She is the emotional one that believes in Revenge Before Reason, readily willing to sacrifice her own life and everyone else's for the sake of justice/revenge. She either gets a sex-change operation later (see above Guesses) or we accept that it's an Alternate Continuity

Mello comes from a mob family.
That explains how a fourteen year old kid can join the mafia instead of getting his ass kicked. It also explains why he's in an orphanage- either L took Mello into protective custody or, being criminals, Kira killed them all. Or both.

Mello is the child of

 * This would explain the gun thing and why when a  shows up, everyone else tries to kill it, but Mello? He just calmly hands it a bar of chocolate. That is so Doctor.
 * This also explains why he - he knew the Death Note wouldn't work on him!
 * That explains why in the manga, we do not see
 * Plus, he physically looks like both  and , as well as   and
 * He could have regenerated into Willy Wonka.

Roger wanted Mello and Matt dead.
You know that Roger hates children? Roger send Mello and Matt away from the Wammy House so they would die from the Kira case and Roger could become Watari for Near. Oh, and Near was the only child Roger liked simply because he stayed out of his way.

Matthew is Matt's middle name.
Let's face it,  is an embarassing name. And it's not uncommon for someone to go by their middle name. So Matt just chose a shortened form of his middle name as his codename.

Matt is a figment of Mello's imagination.

 * It seems like he had no real friends at Wammy's; we see him studying, alone, playing with kids who don't like him, and looking at his test scores, alone. He was so frustrated, trying to beat Near, that he imagined "Matt". Matt was the third-smartest kid at Wammy's, so he could keep up with Mello intellectually, but he had no interest in actually becoming the next L, so Mello didn't have to compete with him. When it came time to kidnap Takada, Mello secretly shot off the smoke bomb himself and imagined Matt doing it. There were no other bodyguards beside Lidner there, but Mello imagined all of them killing Matt because he knew that he was going to die soon, so Matt couldn't live past him. Ohba even says in Vol. 13 that Matt's sole purpose in the manga was to give Mello someone to interact with--his whole purpose in existence is to keep Mello from being lonely!

Matt is a male Diclonius.
It fits! He's an orphan and according to Fanon he has pink hair. Also he is incredibly loyal to one human (Mello) who seems to be his only friend. So that's why he wears the goggles-it's to hide his horns. This also means

Matt saved Mello
Matt doesn't appear until after Mello is on his own again and someone must have gotten Mello medical attention.

Mello wore a magic gas mask.
Mello only wears a little gas mask for protection when he's in the middle of a massive explosion. Yet later he's only scarred on his face! So it must have been a magic gas mask, an Artifact of Doom with a price to using it this Magic Gas Mask dropped by a Scaragami prevents the wearer from coming down with a case of dead but it takes it's payment by eating away at the flesh of the user's face.

Matt is actually the smartest of L's successors.
But he deliberately scores "average" for Wammy's Program and refuses to apply himself because 1) he doesn't want to step on Mello's toes and 2) he doesn't want the responsibility that would come with L's title. As for Matt's major scene in the anime, well, even genii can have errors in judgment...

Matt took out some of the bodyguards
After watching, it's only logical to assume that. He may have had at least enough time to. And even then,. The footage was cut because it lacked significant plot relevance.

Mello is Johan.
The Actor Rule. Also both are blonde chessmasters indoctrinated at an orphanage for a nebulous purpose and kill people.

Mello is Misa's long lost brother.
Why not? Both are thin, blonde, overdramatic, and have a preference for gothic clothing.

Matt's (Mail Jeevas's) code letter would be J.
Because Mello already has "M" and "J" isn't taken yet. (The Wammy's letters already taken are A, B, F, K, L, M, and N.)

Near is an intelligent robot
He doesn't appear to age, unlike Mello; and he survived. The Death Note Mikami used was real, but the Death Note can't kill robots. It didn't work on anybody else because...either they're robots too, Mikami is a horrible speller, or, ummmm...they're all robots.
 * Besides there being no evidence that Mikami's notebook was anything but fake, as Near said it was, if the Death Note doesn't work on robots, it's highly unlikely that the Shinigami Eyes would, either.
 * As mentioned above, Mikami had the Shinigami Eyes. There's almost no way he could have spelled it wrong.

Near is autistic
He's an eighteen-year-old genius who spends most of his time sitting around playing with toys and refuses to get on a plane on his own.


 * A brother of my best friend is autistic, so I did get an impression of the behaviour of persons with autism: And after Near`s very first appearances in the manga, it was practically canon for me, that he was aperson who experiences autism. Especially in the scene, when he and Mello learn about L`s death and Mello gets freaked out completely, while Near doesn`t even seem interested in the conversation and keeps solving a puzzle. Also I recall one scene, in which he builds a perfect model of a city out of dices (if I remember rightly, it was San Francisco). These passages seem to imply that he is indeed an autistic savant. However: In my opinion, most of the time, he doesn`t act like an autistic person would and has abilities such a person wouldn`t have. (e.g. he seems able to interpret facial expressions). So my guesses are: a) I`m mistaken, because said brother suffers from a very severe form of auticism, while Near might be implied to suffer from a less severe one. b) Ohba-san did not have the chance to get in touch with autistic persons and/or portraying him as a person with autism was getting too complicated/in way of telling the story

In the anime, Near didn't write the 'Dear Mello'
In the manga, Mello shows surprise when he sees it. In the anime, however, he gives no reaction, which, given that this Mello, I find it hard to believe he wouldn't react to the person he despises writing something like that. Given that Near is never seen writing anything, his handwriting can't compared to that of the Dear Mello. My guess is that someone in the past or Mello himself wrote that for some reason and he was checking to make sure it was there.

For the record, I happen to strongly believe Near is in love with Mello, but the above WMG has nothing with any sort of shipping be it for or against N/M.

Near is a savant.

 * Similar to the idea of L having Asperger's mentioned above, Near's phenomenally high intelligence, seeming inability to take care of himself (How To Read ranks his "ability to live everyday life" as almost zero, and refers to Lester as his guardian) and odd, almost obsessive habits suggest that he might have a form of Savant Syndrome similar to that of the Rain Man.

Near is the result of an experiment similar to the one described in Ender's Shadow, the companion novel to Ender's Game.
This experminet: -Increases intelligence to amazing levels. -Slows down physical growth. -Decreases lifespan. (Near's lifespan was pretty short compared to the others when we saw it.) Is anyone else noticing similarities here?

Near knew Ratt was Mello's spy, and gave him the alias 'Ratt' to warn him he knew.
Though, I admit Near lacks that kind of subtly.

Near was
Taking Matsuda's Theory a step further,
 * Wow, that is as plasiable of a theory than Matsuda!
 * It would explain the Third Act Stupidity...

Near was controlling Light with the Death Note
Matsuda was right about Near controlling Mikami. However, what he didn't realize was that Near was also controlling Light's actions.In the Death Note, he wrote something along the lines of: "Light Yagami, heart attack, announces that his victory seconds before it is revealed that the notebook used by his subordinate is a fake, goes insane and explains his motives, attempts to write his enemy's name on a scrap of the notebook but is shot at by a member of the Japanese police, dies at 1:15 on January 28" This explains why Light, who never loses his cool, suddenly goes insane and admitts everything. It would be very important for Near to have a confession. Near's morals are questionable enough that he might control Light in order to win the case. He cares a lot for his own safety and he would want to ensure that he wasn't killed before Kira could be brought to justice. Near knows when Light is writing his name on a scrap of the notebook, despite that he isn't really even looking in that direction, and Light is good enough with that scrap in his watch that L didn't even notice when he was using it during the Yotsuba arc. Near would want to prove that Light is Kira, while proving to everyone that Kira is evil, and he might not see any other way to do it, as Light is devilishly clever and wouldn't make mistakes like that on his own. As for Ryuk writing Light's name, that was just because he had promised that he would do so. He saw that Light had only 40 seconds to live and wrote his name down. After all, it's kind of surprising that Ryuk wouldn't help Light and kill everyone. He seems to think Light is interesting and he no doubt knows that if Near wins he will destroy the notebooks and Ryuk will have to return to the Shinigami realm, which he hates. Unless Light's death was a foregone conclusion, it would make much more sense for him to help Light. He may not be on Light's side, but he is selfish and would want to stay on Earth, since he finds it interesting.

Near becomes the next Kira.
He used the notebook on  and he made a deal with Ryuk to stay out of sight until the time is right. He gets rid of everyone who remembers the first case and then when there is no one left to stop him...

Near's final plan really was just a set up
Oh sure,  but that story was fake. In reality, Near was shocked by Gevanni's discovery and decided that his initial plan was too risky, as. Therefore, he came up with a new one. He had his anti-Kira grunts hide near the Yellow Box warehouse once the task force members entered, then when. They then had one of the anti-Kira grunts who looked very similar to Mikami and also had lots of make-up to make it more convincing. But then, how did the actor  Because he was really greedy and took the real notebook from the SPK's HQ and replaced it with a fake and hid the real notebook on himself. He then shot Mikami after he was captured. Ryuk, with the great hearing he said he had in volume 9, was able to hear the gunshot all the way over in the Yellow Box warehouse and left to go investigate during the 30 minutes of waiting. The task force members had their backs turned so they didn't notice. . The actor then made the shinigami eye deal with Ryuk, having already shot all of his associates inside the second warehouse. All of the actor's inner thoughts, such as 'God!' were in fact referring to Near, since he knew.

Misa will live for hundreds of years, and possibly become a shinigami.
""By manipulating the death of a human that has influence over another human's life, that human's original life span can sometimes be lengthened. If a god of death intentionally does the above manipulation to effectively lengthen a human's life span, the god of death will die, but even if a human does the same, the human will not die.""

If taken a certain way, it can be interpreted as the human gaining whatever life the shinigami had collected. If the shinigami had less life than that remaining to the human, the human dies of a heart attack at the original time of death, why the Note says "sometimes." Misa would, barring lethal accidents, slowly become more and more like a shinigami after the original duration of her lifespan. She has had two shinigami obliterate themselves to save her life (one indirectly), and is a prime candidate for becoming a new shinigami, or at least an undying.
 * Jossed by way of How To Read 13: she dies the next Valentine's Day following the Yellow Box showdown. However, I did crunch the numbers, and Misa wound up increasing her overall lifespan by a considerable amount of time despite taking the Shinigami Eyes twice - possibly even because of it, on account of Rem.
 * The manga and anime versions of Misa may have offed themselves but the live action one didn't. So the theory could still work, just only in the live action continuity.
 * Perhaps Ryuk used the Death Note on her just to send her to the Shinigami Realm to mess with Light.

Misa is a fiendish confidence trickster and serial killer
Misa is Really Seven Hundred Years Old, and her behavior is really Obfuscating Stupidity to cover up her true Magnificent Bastard personality and fool shinigami into falling in love with her and sacrificing themselves one after another. Gelus and Rem are just the latest in her inconceivably huge list of victims.

When Misa commited suicide, she became reincarnated shortly after.

 * She was given too much lifespan after Rem sacrificed herself to save her life, so when she killed herself, that extra life she had was used to reincarnate herself. Gelus doesn't count because Misa halved her lifespan twice before she gained Rem's lifespan. But then again, Gelus may have had a lot of lifespan in him.

Misa didn't at the end of the anime
She just happened to be wearing gothic loli and wanted to see the city..Yea. That's sounds good.

Ryuk saw Jealous and Rem mooning over Misa before he ever dropped the Death Note.
So, he investigated the Japanese police, found one with an attractive male child Misa's age, and gave him the Death Note. Ryuk figured that this boy would be able to hunt down Misa when she got her Note if he knew about the Death Note, forcing Rem to sacrifice herself. Things worked out better then he ever expected, to his unending amusement.
 * One problem: Ryuk doesn't find out that Light's father is with the police until the reader does.
 * That's what he says. Ryuk is known to conceal things to amuse himself.

The events of the series were a massive Xanatos Roulette by Ryuk for the purpose of obtaining additional Death Notes.
He starts the series with two, and he would have had four at the end if Shidoh hadn't shown up and taken one. He's just waiting to pick them all up after the events transpire.

Before becoming a Shinigami Ryuk's father was a drinker and a fiend...
Why so serious?

Ryuk didn't toss the notebook at random. He deliberately chucked it at a school.
Oh, he claims it was all just an accident, but he's a known liar. It's as Light explains in the manga when he and L are building a profile for Kira- a teenager would be the most likely to use the notebook the way Kira did, anyone younger would be too scared to use it and anyone older would just use it on occasion to kill people they didn't like. Ryuk knew this. Ryuk isn't very bright but he is immortal. Who knows how many times he has done this before? He might even know exactly what type of human would make the most amusing toy—someone who has never known hardship so psychologically can't cope with having killed someone other than to SNAP in an amusing way... Ryuk might have even specifically targeted Light despite what he says: "you think I chose you because you’re so smart or something?" He knew Light was "so smart" before even meeting him.

Ryuk made sure Gelus' Death Note fell into Misa's hands.
Ryuk introduced Gelus to Misa, and Rem to Gelus, so Misa would meet whoever gets the Notebook first. Oh, and Ryuk drops the Death Note near Light on purpose.

Ryuk is the first shinigami psychopath, and Kira was just a side-effect of a sadistic game he was playing.
Shinigami generally operate on Blue And Orange morality, but there is very clearly something wrong with Ryuk compared to the others. Ordinary Shinigami display few emotions, just apathy (some of them give so few fucks they nearly die from not writing enough names) or compassion (Rem and Jealous). Ryuk, on the other hand, appears to find human death and suffering hilarious and is noted as being considered a weirdo by Shinigami because he diligantly wrote down a lot of names in his notebook all the time. The other Shinigami killed intermittently because it's their job and life source; Ryuk killed lots of people because he enjoys it. However, just writing down human names apparently got boring for Ryuk after a while, and he turned his mind towards something else; murdering his own kind. Ryuk mentions offhandedly that he wrote down the names of all his "friends" in the Shinigami world a number of times, but they didn't die, so he was actively attempting to kill the others before Light met him, he just didn't know how, being unaware of how Jealous bit it. Once it became clear his usual M.O. wasn't going to work on Shinigami, Ryuk decided to play a more subtle game by stealing some dumb chump's (Sidoh's) notebook and electing to play "keep-away" with it until Sidoh ran out of lifespan and died, using the general apathy of his fellow Shinigami to steal their notebooks and starve them to death since he couldn't kill them outright. To this end, he hurled Sidoh's notebook into the human world to get it as far away from him as possible, and planned to amuse himself by racking up as big a body count among the puny humans that picked it up as possible until Sidoh ran out of time and he scored his first Shinigami kill. Things didn't go as planned for Ryuk, and Sidoh's alive and well, but Ryuk doesn't mind; his diversion amused him for a while, and there is nothing to stop him from trying again later.

Mikami is L
Rem was (understandably) pissed about being made to sacrifice herself. So, she writes in her Death Note, "L Lawliet. Suicide. Apparently dies of a heart attack, escapes from his grave with his memory destroyed, adopts an alias, starts a new life and becomes obsessed with Kira. He is devoted enough to gain Kira's trust, but fails at a critical jucture, causing Kira's defeat. He commits suicide out of shame afterwards." However, Rem filled in few details of L/Mikami's behavior post-amnesia other than his obsession with Kira, leading to a methodical, obsessively followed schedule.
 * The Death Note can only control people for about a month, though. He would have had to come back from the dead mighty quick... which presents an amusing image.

Mikami was followed by a Shinigami for large periods of his childhood
During Mikami's time in high school, the 4 bullies and his mother were all killed in the same accident, as well as the "coincidental" times when "he wished for a deletion, it would come". All this points to a sympathetic Shinigami's involvement. Furthermore, none of these killings would have extended Mikami's lifespan, allowing the Shinigami to remain alive. "The god of death must not stay in the human world without a particular reason. Conditions to stay in the human world are as follows:
 * This seems plausible.
 * The manga says "it was all a coincidence". This isn't a character saying this, it's the actual narration. So it must be coincidence.
 * A real coincidence would be if Ryuk was the Shinigami following Mikami around. Think about it. He was probably getting bored even then, and so he might've decided to see if he could convince some human kid that he had magic killing powers just to mess with him. Mikami ended up being way too boring, and so Ryuk would've left after a while, coming up with his 'Throw a Death Note into the Human World' plan afterwards as a much more interesting idea with less work on his part.
 * A rule in the Death Note completely disproves this:

When the god of death's Death Note is handed to a human.

Essentially, finding a human to pass on the Death Note should be done from the world of the gods of death, but if it is within 82 hours this may also be done in the human world.

When a god of death stalks an individual with an intention to kill them, as long as it is within 82 hours of haunting them, the god of death may stay in the human world."


 * It's true that a Shinigami couldn't follow Mikami per se, but it could still watch him from the Shinigami world and kill the people he wanted to die.
 * Well, if say Ryuk was the Shinigami to kill all the people that Mikami wanted to delete, then technically he does have a reason to be in the human world. He's stalking all those people Mikami want dead to kill them, which falls into perfect line with the rules. He could have first came into the world, stalking Mikami's mother to kill her. After writing Mikami's mother's name in the Death Note, he noticed Mikami's "delete" issue, so decided to add the bullies in the Death Note so that they all died in the same accident. After that, he followed Mikami to get names of people he could stalk to kill in the Death Note. As he has 82 hours per life he's taking, taking many lives gives him 82 hours longer that he could spend in the human world each time he kills. At some point, either he was killing too much or just got board as said above, so returned to the Shinigami world.

Mikami had a Death Note before the start of the series
Most Shinigami don't seem to care much for the human world beyond increasing their own lifespan (aside from Rem, Gelus, and Ryu - Shido doesn't count, since he's only there to retrieve his note). So, to explain all the coincidental deaths and deletions around Mikami, he used to have his own Note, which he gave up at some point.

Taro Kagome from the pilot chapter grows up to become Teru Mikami.
After the incident in the pilot he changes his name when he's like put into witness protection or something. He forfeits ownership, loses his memories, and later regains them at some point because Ryuk thought it would be funny. He then goes on to write the story of Death Note once the world has fallen under Kira's control for the sake of plausible deniability.
 * Also, he still has the Death Eraser and eventually brings L back to life on Light's request because Victory Is Boring.
 * Maybe all of those deaths he saw as a child was actually things he wrote in the death note and then he gave up his death note losing memories but the deaths were mentioned so Taro remembered. The end picture with Taro and Ryuk could have been when Light gave Teru the notebook but Ryuk gave it to Taro instead. Taro killed Mikami and replaced him with himself. He became methodical because Taro was afraid that any change in his behavior would make it apparent that he was an imposter.

Mikami pulled a Heel Face Turn before he died
After Light said "I Don't Know This Guy" in the last episode, Teru Mikami finally realised that he had been used, and saw how evil Light had become. Upon realising that he'd dedicated his life to serving someone who, in his mind should be DELETED, he broke down and killed himself

Mikami and Light are Childhood Friends.
But they lost touch after Mikami's mother died and Mikami was shuffled off to some orphanage and went to a different school. That would explain why Light chose him so quickly when he saw him at the Kira Rally. Light could have even been one of the kids that Mikami saved from bullying!

Ryuuga Hideki is Ide
Apparently, Ide's surname, is, in fact, Hideki. Isn't that a rather odd piece of happenstance? My theory is that Ryuuga Hideki doesn't actually exist - it's Ide impersonating an idol as part of some kind of case, a deception which he continued after he would have normally ended it in order to get closer to Misa. Ryuuga's face, not Ide's, is in fact the real one. The reason Ide mistrusts L is part of a long-standing rivalry between the two - that's why L called himself Hideki when he met Light, in order to trick Light into killing Ide. Ide came onto the task force in the end because he was so fed up of having to deal with Misa that even working with L would be preferable.
 * Well, right, but Hideki is a first name, not a surname, on both cases. Ryuuga and Ide are their surnames. Which actually makes a bit more sense -- the way they had of dealing with fake names on the investigation team was changing their surnames around, that's why L calls Light by his first name and not "Yagami-kun" anymore.

Matsuda really liked Light
Yes, that way. The last chapter provides the strongest evidence for this.
 * The drooling over his sister was just displacement.
 * "Your reason is not actually reasoning but...desire." Dude, this part probably makes it canon.

The entire series fell into place exactly as planned...by Matsuda
No, this makes no sense whatsoever. But wouldn't it be so freaking cool?
 * You wouldn't happen to know a guy on deviantART named Derrot, would you?
 * This can work... Light did say in the manga that he'd met Matsuda at dinner once before... Matsuda could have been the first one to get Ryuk's note. He convinced Ryuk to drop it outside Light's school. Knowing that Light was like-minded when it came to justice from meeting him and hearing about him from Soichiro, he predicted that Light would kill criminals with the Death Note. However, he realized that Light planned on killing him, so he arranged for Mello to abduct Takada, leading to Light's exposure and giving him an opportunity to eliminate Light without being arrested. He himself had a scrap of the note taped to himself at all times, and he managed to retrieve several pages from the notebook so that he could continue killing not long after the series ended, starting with Near and the SPK, whose names he knew thanks to Mikami.
 * It makes sense. Matsuda had his own struggles with morality and alikeness to Light, so he decided that Light should carry his actions out with Matsuda not getting blamed. Matsuda was happy with how Light had recreated the world, and he wanted to go on to be the god of the new world and killed off Light to get his position as the leader.

The series was actually a hallucination/desperate escapist dream by collegestudent!Matsuda.
Think about it. Matsuda is a young college student, interested in law and detective work and studying for it at a Tokyo college. L is an extremely intelligent young man at the college who Matsuda is baffled yet intrigued by. Light is a popular boy who is similarly intelligent as well, with flocks of girls at his feet. Matsuda is becoming intolerant of the world in general. As such, he begins clinging to escapism as a means to escape the disappointing world around him, being fueled by self-doubt and stress. His 'Death Note' mental universe becomes more real and eventually he becomes entranced by the 'dream'. He also becomes significantly more conflicted about issues and becomes more attached to L and Light. All the events in Death Note had somewhat pertinence to Matsuda's life- L's death was a manifestation of Matsuda's fear that the only seemingly sane person in his life would die, and it was partially Matsuda's fault to boot. Light's death was more of a guilt-trip for Matsuda, as a manifestation of his self-doubt about his detective skills and as a partial guilt-trip for L's Death Note death (Matsuda feels as if L died because of his lack of detective work and common sense). College!Matsuda slowly becomes more and more antisocial, conflicted and over all scared. The tension only mounts more when, in a law class, they get into a debate about what justice really is. Of course, L and Light have conflicting views. This causes Matsuda to question his very morals. Do I hear yays or nays?
 * You didn't mention Soichirou at all. I'm going to have to go with "nay".

Everything in the series happened because Ryuk wrote it in his Death Note.
Ryuk, out of boredom, wrote down the events of the series in his Death Note, dropped his other Death Note in the human world, and kicked back to watch the show. As time went on, he continued to write things in his Death Note, finally ending with Light's death. It would certainly help to explain why, as a kind-of important character, he's never actually seen doing anything- as the "director" of sorts to the chain of events, he wouldn't have to.
 * But the Death Note can only control people for 23 days... unless he was writing something like "* random name* . Drowns. Before drowning, he happens to pass a young man who is secretly Kira on the street. Said man then begins to plan a massive memory gambit wherein..."

Mogi was working for Near or L from the very beginning.
As improbable (and awesome) as Matsuda running the show, yes, but his dedication to behind-the-scenes work certainly opens up the possibility that, say, Mogi was a former acquaintance of L's, similar to Naomi Misora, and would thus have connections that expedited L's initial movements in the Kira investigation. If his influence wasn't THAT good, then he'd at least have known of the true purpose of Wammy's House and found a way to contact Roger in secret after LADIES NIGHT, confirming the notification from the inactivity timer on L and Watari's computers. Either way, he would eventually set up his capture by the SPK to leak the more Light-centric information on the case.

Mogi has PDD-NOS.
Which could explain his discomfort in showing emotions and his hesitancy to interact with others.

Sayu Yagami was somehow behind everything.
For one, she is one of the few characters that who can manipulate Light and live to tell the tale.... ("I totally don't get this, could you do my homework... I mean show me how?" "But mom, I'm going out with friends today!")
 * In fact in the manga Light tells Ryuk that he's trying to make the world a safer place... for Sayu.

Soichiro Yagami is L's father.
It's not mentioned when Soichiro married Sachiko, and it's not impossible for him to have had sex with other people before marrying, possibly helping conceive a bastard child. L is older than Light, and there's no indication how soon Light was born after their wedding.
 * They also don't look anything like each other. And Britain is pretty far away from Japan. Is there any real support for this?
 * Well, does Light look like Soichiro at all? Plus, in The Last Name movie, L told Soichiro he'd been like a father for him...
 * Wait, are you insinuating that Soichiro isn't Light's father?

Some say that he got his start doing incest Hentai, and that his son is secretly Kira.
All we know is, Soichiro Yagami is the Stig. "Ide: Do you remember what happened to the first Stig?
 * Well he did drive a van through a TV station door (or...whatever that was in the movie). That sounds like something the Stig would do.
 * And he looks good in a helmet!

Matsuda: He got shot by Mello.

Ide: Because-

Matsuda: Because we used nitrous."

Light and Sayu have a repressed incestuous attraction to each other
The girl Light dates when he meets Ray Penber looks like an older Sayu, and later on, one of the girlie pictures he looks at again looks like his sister. Meanwhile, Sayu fangirls the movie star Hideko Ryuuga, who bears a passing resemblance to Light.
 * Thank you! I knew I wasn't the only one who thought Ryuuga looks almost exactly like Light! Hmm, that's not even taking into account the fact that Sayu seems to be the only person Light cares about other than himself. He never did bring himself to kill her, did he...?

Yagami Soichiro was about to be assassinated.

 * Someone should've investigated what would have happened had his father lived twice as long as he did from the time he gained the Shinigami Eyes. Who knows which Xanatos Gambit could've been unraveled.
 * Or someone should write a very good fanfic about it.
 * There's this parody comic.
 * Not that we actually know that the Rules work that way.
 * Or do we? I didn't go through all the ones from the manga.
 * Soichiro wasn't necessarily going to be assassinated, it could have just been an ironic second heart attack that could've killed him.
 * Let's just agree that Soichiro was going to die that day no matter what, since if my math's correct he only lost a few hours of lifespan when he took the shinigami eyes.

Yagami Soichiro would've gotten fatally wounded in the assault on Mello's warehouse.
The Shinigami eyes cut a person's lifespan in half, but Soichiro died only a couple hours after getting the eyes. Also, remember, he didn't do the eye deal until they were already poised for attacking Mello. Here's my theory on the "original timeline"; if Soichiri hadn't gotten the eyes, they would've all rushed in, and attacked Mello in a more conventional manner, I.E. by shooting him, or trying to anyway. However, Soichiro still would've gotten shot up pretty badly since he would've hesitated shooting, as he apparently hasn't killed anybody before (or maybe it was the believed 13 day rule that made him hesitate, who knows?).

If Soichirou hadn't assumed the Death Note, he would have committed suicide the next day.
Pretty straightforward.

Sayu is only woman who Light feels attracted to.
It would explain why Misa and Takada don't arouse him, by any means, and why, even after becoming completely sociopathic under the Death Note's influence, he would continue to protect his little sister. Until their parents died and he finally had the chance to put his hands on her. Note that I specifically used the term "woman', so....

The unnamed shinigami in the first Re-Light special is Soichiro Yagami.
Due to Soichio's unique circumstance of he was granted an equally-unique afterlife: being reincarnated as a shinigami.

He completely remembers his life as a human. He is seeking out Ryuk to find out how the Death Notes get into the world. Being the decent guy he is, he plans on using this to find a way to prevent any shinigami (including himself) from ever entering the human world again. He doesn't want another Kira to emerge. .
 * Soichiro is This Troper's favorite character and loves the idea of

Sayu becomes a Kira.
According to Word of God Light probably switched the notebook that was in police custody and considering his escalating hubris at the time he may have hidden it in his own house. Sayu is just recovering from her kidnapping and the deaths of her father and brother when she stumbles upon Light's hidden notebook. Sayu hero worshipped her big brother and after she pieces together what happened she starts killing criminals because no one should have to go through what she went through at the hands of the mob and she wants to avenge her brother and by acting as Kira she will flush out the ones who killed him and she probably succeeds too, seeing that no one suspects the ditzy-looking traumatized cute girl who is, according to the guidebook, actually a genius who is as smart as Near.

B is a shinigami
He committed some crime; as punishment, he had his memories erased and was turned (mostly) human. That's why he has shinigami eyes and lacks a visible lifespan despite not owning a Death Note.
 * Since he winds up dying in the end as one of Light's otherwise unimportant victims, can we consider his human incarnation a Level 3+ Punishment? (For those lacking the manual, punishment for breaking Shinigami conduct is numbered in decreasing order from Level 8 to 1, plus an Extreme Level. Any punishment of Level 3 or greater (2, 1, or Extreme) warrants the death of the Shinigami after it is conducted - in this case, the death may also be part of the punishment.)
 * Yes, but this brings up the question of whether what B did is considered worse or better than intentionally extending a human's lifespan.
 * Now hold on. We never know for sure if Light is the one who kills Beyond. All Another Note says is that he "died of a mysterious heart attack in prison."

B is part shinigami.
I know, there's already a guess for B being a shinigami, but this one says he's only part shinigami. One-sixteenth shinigami, for example. There's a rule that shinigami can't have sex. Before that rule was in place, a male shinigami went to Earth, interacted with a female human, and eventually had sex with that human. That female gave birth to a human born with shinigami eyes. Hence, the rule banning sex was made. Now, it could be as close as B's father was really a shinigami, or this could be an inherited trait, such as every other generation from the initial half-shinigami inherited shinigami eyes.
 * So the part about it being impossible for humans and shinigami to have sexual relations is just propaganda
 * The rule exists for some reason.
 * Exactly. If it isn't POSSIBLE than WHY would there even NEED to be a rule forbidding it?
 * Maybe to stop them from trying? Think about it—all brands of bulletproof glassstop bullets, but if a company dares you to put a bullet through theirs, suddenly everybody’s trying.
 * This would also explain stories in the Old Testament of angels who came to Earth and took human wives.
 * 

L, Beyond Birthday, and Teru Mikami are related.

 * They are similar in appearance, L and BB are orphans, and Mikami has an absent father...

Beyond Birthday is a Reincarnation of the dark wizard Raistlin Majere.
Both are genius Chessmasters with eyes that see how everything dies that will do anything to further their goals.

L and Beyond Birthday are the same person.
The Beyond personality came about because L became so emotionally repressed thanks to being put through Wammy's Program. He needed Misora's help because his opponent was both too alien and too similar to his own thoughts and so this was one opponent he couldn't beat himself.

What a twist!

He doesn't  afterwards because Wammy's estate is that wealthy and has access to leading edge and nonexistent technology and medical care.

Beyond Birthday is L's clone.
B is the result of one of L's enemies, an Evilutionary Biologist cloning L spliced with a little bit of Shinigami DNA (so that he has the Shinigami eyes and can see L's real name) to create for L an ultimate enemy. The Evilutionary Biologist then leaves the clone on Wammy's doorstep and watches the ensuing chaos.

Beyond Birthday is not his real name.
Because seriously. Beyond. Birthday. When Mello narrated the book, he wanted to hide BB's real name so people wouldn't be able to use the information to piece anything about L or Wammy House together. This meant renaming him and, since his initials were a major part of the murders, everyone else with initials that pointed to him. Mello gave the people weird names to emphasize this and to confuse people. Beyond Birthday's real name was something like Nathan Nolan, his victims were Natalie Newhouse, Nick Neilson and (since their initials upside should resemble a lower case "nn") Ulrika Ulverston.

Wammy's House is in fact the central organization from Men in Black.
Well, with all the One Letter Names around, there ought to be a connection. They're both top-secret, as well. Also, the Shinigami are aliens.

Wammy's House is The Academy.
Think about it. A creepy place that takes kids and creates creepy teenagers and young adults out of them, with abnormal abilities, who also end up being pretty much broken, with weird quirks and actions, along with the ability to torture and kill without remorse. Both fit that perfectly.

L's successors' growth was intentionally stunted by the Wammy House, giving them their youthful appearances
Mello looks like a little girl at 17 years old. When Near's about 19 years old, he still looks about 7. This is because of the Wammy house's experience with L, who was not only extremely intelligent, but also very strong, making him a hazard and a complete loss if he ever decided to escape. Because of this, the Wammy house drugged L's two successors with an anti-growth hormone, making them too weak to escape or cause as much damage as L potentially could have. Mello still exercised and remained strong. Near played inside on the floor with his puzzles, leaving him incapacitated and making it extremely difficult for him to even move off the floor. While he remained extremely intelligent, the Wammy House's drugging has left him immobile and parasitic to whatever organization takes care of him.
 * L himself, curiously, can easily blend in with high school students in his mid 20's, so it's possible the experiments began with him.
 * Or L's really good with hypnosis, and this whole time we haven't even seen the real L yet. So far it's only a random high school student that played too many video games hypnotised into believing that he's the real deal.

Wammy House feeds its charges from L's generation and later APTX-4869 when they are old enough for their bodies to handle it.
It didn't work well on L, or they hadn't perfected it. It worked better on Mello and Near.]]

All the chairs at Wammy's House have really strange design.
That would explain why everyone from Wammy's sits so bizarrely. L's pose is famous, but his successors don't sit normally either. Near seems to kneel or lie down most of the time, and Mello sort of lounges. Admittedly, I myself don't really sit normally, but still...
 * Well, I sit with my legs crossed, even if the chair has arms. So, it doesn't mean anything besides the fact that they are strange, just like me.
 * What about Matt? He sits normally.

The Wammy House is a genetic engineering laboratory.
This would explain why so-called orphans that shared unusual idiosyncracies would congregate in the same agency. The story about the orphanage is just a deterrent to industrial saboteurs. L is a prototype, and Mello and Near were made from modifications on his template. This also explains why Near was talking about being his "heirs" and surpassing him.
 * BRB, writing fanfic where the Next-Generation Investigative Forces unit "Wammy's House" goes rogue, demanding a billion dollars and L's body to prevent a nuclear launch.
 * METAL NEAR?
 * It can't be!

Wammy's House is a Division of the Company.
A morally grey organization that trains / experiments on special children (i.e. superintelligence, Shinigami eyes, etc.) for an equally ambiguous purpose of becoming the next L and "fighting the forces of evil."

Wammy's House is one of the Peterson Schools.
A top secret program that rounds up genius kids who all, "coincidentally," one day become superheroes or supervillains...

Wammy's House is a training branch of VFD.
I mean, think about it. Whammy's House takes orphans and trains them to be detectives. And all of the people who leave go by an initial, like VFD members. It's fairly obvious.

V was trained at Wammy's House.
Let's see... British guy, a mad genius who fights against a dystopian state, who hides his identity and is only known by a letter... and Remember, remember the 5th of November-that's the day of !

EVERYONE is
They are hiding out as extras in Full Metal Panic.

The previous universe of Death Note was Neon Genesis Evangelion.
Think about it! L is Gendou, Near is Rei, Light is a twisted form of Shinji and Kaworu, Mello is Asuka... This works because L shows Gendou-like secrecy and Chessmasterness, while Near is a tykebomb which has been effectively trained by L since his childhood (albeit indirectly), and Near and Mello have their conflict...

Death Note is a Stealth Parody of Shonen tropes
Think about it. Despite being a dark crime thriller with a megalomaniacal mass-murderer for a protagonist, when you get down to it it contains all the basic elements of a typical shonen series, albeit in forms twisted nearly beyond recognition: a young, justice-loving Chaste Hero Chosen One (a narcissistic Knight Templar with delusions of Godhood/being the Chosen One) who discovers magical powers (a notebook that can be used to instantly murder anybody) and gains a Spirit Buddy (an amoral embodiment of death), makes a Worthy Opponent rival (a detective trying to apprehend him for his crimes) and picks up a persistent Genki Girl love interest (a vapid pop idol who's fanatically obsessed with him and, despite barely knowing him, is instantly willing to kill for, die for and marry him). If the satire was intended on the part of Tsugumi Ohba, he/she sure hasn't let on.
 * Or even a stealth parody of happy fun kids' movies. Specifically, remember that one about the bullied kid approached by a goofball monster wearing punk accessories? The one from a world of monsters that preys on humans. Now remember the pilot chapter. Take a good look at Howie Mandel's eyes and mouth.
 * That explains everything! Also Misa seems to be a parody of typical shojou tropes, especially the Magical Girl genre: a young, beautiful, yet ditzy girl is granted magical powers (see above) by a (not so) cute Non Human Sidekick (a gross, monster-like creature), is fighting evil by the moonlight (by murdering criminals and innocents), finding a Mysterious Protector (In Name Only, who just uses and manipulates her, gives a shit about her as a person and actually wants to kill her in the beginning) and falling in love with him (as in: becoming completely devoted to him unrealistically fast, dedicating her life to him and being completely obedient. (Like any good (soon-to-be) wife should do!)) Bonus points, because she teams up with demons, instead of fighting them, like a typical Magical Girl Warrior.
 * And let's not forget Martial Arts: L knows Capoeira.

There are so many weird names in the Death Note universe, because people try to confuse death note users
Even though the concept of Kira didn't exist before the events of the story, there were other Death Note users, and people got used to that revealing one's true name can get them killed. So, in the same way as certain tribes used to give infants weird names to confuse evil spirits, the inhabitants of the Death Note Universe subconsciously got into the habit of giving confusing names like "Merrie" for Mary, or "月 (tsuki)" for "Raito", to decrease the risk of heart attacks.
 * So the habit of giving kids really stupid names these days is actually a survival mechanism to protect us from the Death Note holder who has been killing off celebs?

The Death Note universe is The Inkworld a few milennia in the future.
Between the events of The Inkworld Trilogy and Death Note, somehow the White Women were mutated into Shinigami and each had their lifespans bound to modified White Books that would later be known as Death Notes. The reason it's so much like our universe is because of Meggie, who was able to influence history through her inventor husband Doria.
 * And by extension...

All the events of Death Note were one massive Xanatos Gambit by Orpheus to get revenge on Mo and Dustfinger.
Basically, after running away, Orpheus read aloud something he wrote about the White Women being bound to corrupted White Books that could only kill, then read that, generations later, a descendant of Dustfinger's would use one of these Books to kill a descendant of Mo's, only to die defeated and alone shortly afterward. Then, a few milennia later, Light uses a Death Note (he technically used the Shinigami whose Death Note it was, but it still counts as 'using' the Note) to kill L, only to die a few years later of a heart attack after being shot five times and being utterly crushed by Near.

The second arc never happened.
It was all Light's nightmare or a simulation he had during the Yotsuba arc and he became so unnerved by it he decided to give up the notebook and remain as L's partner. Yeah...

Nineteen Eighty Four is what would have happened if Light had won.

 * So that'd make Light Big Brother?

Ryuk is a Time Lord.
Amazing this hasn't been brought up yet.

The Shinigami are Time Lords
Specifically, they're a bunch of renegade Time Lords having used up their regenerations. They've been experimenting with genetic engineering for this. The Death Note has both TARDIS and Chameleon Arch technology in it,allowing them to feed.Part of their reason for this is that, like the Weeping Angels, they feed on your potential lifespan-only they just straight up kill you. Ryuk is a clone of the Master.

The Shinigami are cousins of the Weeping Angels
They "gain" lifespan in a similar way as the Angels do (the Angels transport you to a different timeline and feed off the potential energy. The Shinigami kill people and gain more lifespan). Their powers are only limited to humans, so the Time Lords don't care (who cares about the cosmic equivalent of cavemen?)
 * The Doctor!

The death note is a Tardis.
It's bigger on the inside (it has an infinite amount of pages) and it can manipulate events in time and space but it's malfunctioning so that it always brings about the death of those that go inside it.

Aiber is A from Wammy's House
A is a Time Lord who committed suicide to escape Wammy House. However, he still wished to beat L and tried to do so by both exceeding his detective skills (while using the name Eraldo Coil) and by being a con-man that L wouldn't be able to catch. Unfortunately, he failed on both fronts thus losing the right to use the alias "Eraldo Coil" and being forced to either help L when needed or spend a great deal of time in prison. Hence why Aiber uses an "A" to identify himself and is able to act as Eraldo Coil during the Yotsuba arc without anyone noticing any discrepancies between his behavior and Eraldo Coil's known behaviors.

L is a Time Lord
He regenerates into Near. Now, one might ask why Near would have to deduce certain things all over again when he already came to that conclusion as L. The answer is that, like the eighth Doctor, Near is suffering from partial amnesia.
 * In addition to the above...

The time lord that is L/Near is a regeneration of Mytho from Princess Tutu
Near, who resembles Mytho is already a regeneration L and Aeon. L and Near have cut out parts of their heart in order to defeat Kira. Notice that neither are ever scared or lonely or loving or anything that might get in the way of their duties. In fact, all they might have is Curiosity. After that, Near reconstructs most of or all of his heart and becomes Aeon.

L is a Time Lord and Naomi Misora was once L's Companion.
They had many adventures of horror and wonder together but she eventually returned to get married to Raye.

Light is also a Time Lord
...Ergo Light is the Master.

Light is the 10th Doctor. The TIME LORD VICTORIOUS!
For so long he lived in boredom and despair. There was so much that was rotten but there was nothing he could do. But then one day he realizeed the rules, time, this world-they are his to manipulate! Being the only one of his kind (super genius) around didn't make him some freak, it made him VICTORIOUS! ""I'm sorry. I'm so sorry.""


 * So would that mean that Misa is Rose Tyler, Mikami is Jack Harkness, and L is the Master?

Light is a Time Lord and Ryuk is his Companion.
Who says Companions always have to come from Earth?

Light Yagami is a Time Lord and he regenerated into Lelouch Vi Britannia.
Who in turn regenerated into Paul Atreides...

L is Light's regeneration gone back in time to stop himself.
However he doesn't remember everything from his past regeneration.

Mello is a Time Lord.
I think Mello is
 * This would explain the gun thing and why when a  shows up, everyone else tries to kill it, but Mello? He just calmly hands it a bar of chocolate. That is so Doctor.
 * This also explains why he - he knew the Death Note wouldn't work on him!
 * Plus, he physically looks like both  and , as well as   and
 * He could have regenerated into Willy Wonka.

Mikami is a Cyberman.
It's so OBVIOUS! ''DELETE! DELETE! DELETE!''

L is The Master
In the episode where he  L mentions that he can hear bells. While everyone assumed that this was something to do with his human past due to the opening flashback with Big Ben, that isn't necessarily true, and if it is, may actually be part of the fabricated memories implanted when he chameleon arched. When The Doctor psychically connects with The Master in EOT, The Drums...don't really sound like drums. If they were quieter, they could easily be mistaken for bells, and they might well be slightly dulled by the chameleon arch. While this may lead some fans to think that, due to Chameleon Arch personality flips, this makes Light The Doctor, it is my opinion that Aiber is actually The Doctor. What's the one piece of character development we got about him? He hates guns. It's entirely possible that, (Although not true every time due to 10 training his students in rifles and machine guns as John Smith) that the flip's severity varies, and that when they chameleon arched for whatever reason, The Doctor got a very mild one which put him on the wrong side of the law but left him a mostly peaceful man who despised killing, thus his willingness to work the Kira case, while The Master got a somewhat more severe flip which, while it still left him a somewhat cold manipulator, brought him much closer to good.

L named Near and Mello as practical jokes
Near is a distant and detached savant. Mello is incredibly emotional and crazy. L thought it was funny to name them what they weren't and to make their names start with the letters that follow L, M and N.
 * Not to mention, that name order implies that Mello should have been first.
 * Well, actually Word Of God states that Mello was supposed to be Near's name and Near was supposed to be Mello's name.

The theme naming goes much further than this
This really is trivial, but: Kira, L, Mello, Near? Coincidence? I doubt it. The authors are Ohba and Obata. Can we keep this up?
 * Raye Penber. The novel includes a dead character named (of all things) Quarter Queen.
 * Don't forget Rester.
 * Ah ha! Fridge Brilliance! Mello is before Near because either he came to the orphanage before Near or because of the fact their designs were accidently switched in the esign phase.
 * S...Soichiro!?
 * ...or Sayu! Presenting Death Note 2: Sayu's Revenge!!!
 * OH DEAR LORD...
 * Tanaka......or Takada, but the former is somehow more terrifying.
 * Ukita. Good luck finding a V.

All the confusion over Tsugumi Ohba's gender is EXACTLY AS PLANNED.
It seems that a lot of people consider Ohba-san male when evidence exists to the contrary. A lot of indirect quotes attributed to Ohba are printed as "he said" rather than "she said," so much that it has to be intentional confusion to keep readers from suspecting that a woman can create such a dark tale as Death Note.
 * ...If she's even a woman. Turns out "she's" an asexual self-fertilizing hermaphrodite. Hey, if it works for Vaarsuvius and Ash's Pikachu...

Death Note is based on the They Might Be Giants song "No One Knows My Plan"
Seriously, the song perfectly shows Light's thoughts when is imprisoned by L.
 * I made an AMV just for you, fellow troper! No One Knows My Plan

MOST of the main characters have traits of mental disorders, if not the mental disorders themselves.
Light is almost certainly a psychopath, at least when he possesses the death note. Mello has low emotional control. Misa falls in love with Light in an absurdly jealous way and says she won't hesitate to kill anyone Light even PRETENDS to go out with. Near and L are both on the autism spectrum. And Teru sticks to rules and obeys authority without question. Read up on the DSM's personality disorders, then compare.
 * More than the Lord of the Rings characters!

The sequel manga chapter was not done by the original creators.
Certainly, Takeshi Obata didn't do it.


 * 1) All the lines are thicker, and everyone is a bit off-model - most noticeable with Matsuda. This could be attributed to years out of practice, but then there's item two:
 * 2) A handful of chapters after first showing the N logo, Obata made a conscious decision to change the font from Cloister Black to Olde English - a subtle cue that things are a bit different. This holds in the epilogue. But in the sequel manga chapter, we're back to Cloister Black.
 * 3) Near has been aged up. But he was last seen at eighteen. Not only is Obata bad about aging anyone up, but Near's appearance of having caught the puberty train in the two years since we last saw him goes against biology.

As for Ohba - well, that's harder to determine. Writing is more mutable than it should be. That said, though: Mello - first seen shaking the living hell out of a hapless messenger of bad news - did not get where he was by winning any apathy contests. Least of all where L is concerned. And yes, it's fair to say that L (unlike Near) does, in fact, give a damn.
 * Agreed. Near never meeting L also raises the question, "how the hell does he know what he looks like?" He plays with the L finger-puppet he made in that chapter, and he made an L mask that Light can identify immediately. And it's not at all unreasonable to assume there were no photos of him -- there were none of Near or Mello.
 * On a side note, it's interesting that the manga up to then had held some degree of logic in all the, well... Wild Mass Guessing. But here, we have a story wherein at least three respectable detectives (one an alleged super-genius) and the Japanese public at large immediately deduce that there's a magical killer about based on the sole evidence that.....old and sick people are dying.

Everything was just as planned... by Rem.
Realizing what Light was up to, Rem decided to cut a deal with L. Rem and L fake their own deaths, and L works in the shadows to take down Light. L is smart enough to realize that if he dies it would be impossible to ensure that Light gets taken down (it seems like it required a pretty big Idiot Ball to do him in). When Light finally is killed, L can show and explain to Misa about how touching a Death Note gives someone with a strong sense of justice the ability to eventually come back from the dead. That keeps Misa from committing suicide, since she'll want to see Light again, Rem manages to kill off Light without dying in the process, and L can work from the shadows to bring down Light. Obviously, the plan wouldn't work if Light knew L was still alive, so L is forced to use extremely indirect methods (like sending a message to Wammy's house from his Mac), and possibly even posing as a Kira supporter named... Mikami. The data deletion Watari did was to cover up the preparations for L to fake his own death. L obviously hid some sort of temporary coma-inducing drug in his tea (you can see the teacup just before he "dies"), and had Rem dig him back up once it wore off.

The Death Note anime is a Xanatos Gambit in the style of...
...Douglas Hofstadter's Goedel, Escher, Bach: An Eternal Golden Braid. In one of the chapters, he points out that it's impossible to hide the end of a story from the reader simply because of the number of pages left to be read. They can't be left blank, either, because then it becomes equally obvious for anyone who flips ahead. His proposed solution is to end the story before the number of pages run out, and then keep writing, incorporating things like Character Derailment, Idiot Ball, Villain Ball, introduction of new characters, unforeshadowed plot twists, Genre Shift-ing, and other story-killing devices to let the perceptive reader know where the real story ended. And this is exactly what happened in the second half of the Death Note anime.

Death note's creator is a Nietzsche Wannabe
That would explain the Crapsack World, Karma Houdini Shinigami, lack of an afterlife, Black and Gray Morality, and ambiguity surrounding whether what Light is doing is truly evil.
 * I don't know about that. Towards the end Light becomes more clearly villainous, and he bites it in the end.

The main characters represent the seven deadly sins
Main characters meaning the four Kiras and the three detectives
 * Light is pride. His incredible arrogance is the cause of all his mistakes (without it he might well have won) and towards the end seems to be his main motivation.
 * L is gluttony. This doesn't really need explaining.
 * Misa is lust. A bit dodgy here, love would be better, though she certainly inspires lust from others.
 * Higuchi is greed. His motivation seems to be "money, cars and women".
 * Near is sloth. He never even manages the effort to stand up. Also his style is to watch other people rather than make the moves himself until the very end.
 * Mello is envy. Directed at Near.
 * Mikami is wrath. Unlike any of the others he really seems to enjoy killing just for its own sake.

In the pilot chapter, Taro Kagami writes Death Note.
Fast forward to the ending, and you see people gushing over the newest 'in' thing, Death Note. An older Taro is seen smirking and looking over a quiz about it in a magazine, while Ryuk looks over his shoulder. While others speculate over whether it's real or not, Taro KNOWS it's real, and is capable of writing a story around it, which later gets picked up for movies and television.


 * Or, alternatively, Taro Kagami IS Tsugumi Ohba.

The next human to have a Death Note will take advantage of the unlimited pages.
He or she will tear out a few hundred pages (or a few thousand depending on patience) and deposit them in random recycling bins. Maybe leave a bunch of pages with the margins carefully cut off on different bulletin boards, write a petition or "leave your name and phone number for [purpose]" on the main part of the page and a date of death on each line in the removed margin, or do the same thing with one of those "write your name and send it forward" chain letters to eradicate more specific (gullible/annoying) people.
 * Darn, you discovered my plan! Now I'll have to take another plan for the extinction of the human race!
 * Or simply throw a million pages off the top of a tall building, and let the human race finish itself off.

The Whole thing was one big Prank
a rather powerful friend of lights or a friend with connections organized the whole thing fake news reports, blanks, the works and even hired some actors to portray Shinigami and paid off others to pretend they didn't notice. and in the end Ryuk looks in to Lights face and whispers "surprise"

Light, L, and Misa were named as Shout Outs to the original Macross.
Think about it. "Light" is the English translation of "Hikaru", "Misa" is well, "Misa"...and "L" really stands for Lynn Minmei.
 * Almost: "L" is a consonant swap of "R" for Roy Fokker. It's a little known (read: entirely fabricated and possibly Jossed by How To Read 13's comprehensive guide to the contents of L's stomach) fact that the last thing he had plans to eat before his untimely death was pineapple salad.

Watari and the King of the Shinigami are at war
Light is manipulated by Ryuk to fight for the King of the Shinigami. L was raised by Watari to fight the Death Note users. Light builds up a group of Death Note users in Misa, Hirugushi, Teru, and Kiyomi. Watari has the detectives of A through Z with L being the leader. In the all out war both L's and Light's groups continue to fight until they are all dead.

Death Note is an experimental MMORPG
in anime style. The Shinigami are admins/developers, and their world is a developer isle of sorts. That you go to "Nothingness" when you die is a way of saying that your character is deleted/sakujo'd when it dies. Feel free to add to this.
 * Well, that explains the "see somebody's name written in midair above their head" thing.
 * Did you write this, by any chance?

The actual Star Boarding chain is: Rem -> Gelus -> Misa -> Light
Rem's attachment to Misa was her way of honoring Gelus's memory.

Tsugumi Ohba is a woman.
Why else would he/she emphasize that his/her gender was a well hidden secret? Most Writers Are Male so that suggests that any mystery being intentionally attached to Ohba in regard to gender would be a hint that he/she is a woman. Also, reading through the interview in How To Read 13 creates the distinct mental image of a woman. I've tested this by showing it to friends then asking what gender they think the interviewee is.

Death Note is seemingly sexist as a plan by Ohba.
Ohba is actually a woman, but doesn't want to make that obvious. So she writes the gender roles as she thinks a male would, and it turns out it can be viewed as sexist. But its not sexist, just a female trying to imitate how a male would view females. And I suppose the plan worked anyway, because many believe that the writer is male due to the gender roles in the story. Exactly as planned.

Near and Ryuk were working together.
Somehow, Near and Ryuk made a plan together to overthrow L so Near would be the greatest detective in the world and Ryuk would ease his boredom.

Misa has Rem's Death Note in the finale, and Near retreives it later.
Somehow, Light switched the Death Note in the safe for a fake, but then Misa switched the real Death Note for a fake later. Therefore, when, Misa had a Death Note. However, she bounds it to Ryuk, so he could stay in the human world. When Misa commits sucide, she has the Death Note with her, and Near or one of his allies, retreives it and locks it up.
 * And then it is stolen by a master thief.
 * Aforementioned master thief known as John Mischief.

Roger and Watari are boyfriends.
You wonder how Roger hates children and yet runs the Wammy House? This is why.

The unnamed shinigami is Tai
Look at that hair and those goggles

Naomi actually didn't die.
She was unknowably pregnant with Raye's baby, granting her immunity to the Death Note for nine months. Light's confession to Naomi turned out differently. She considered suicide, but after finding out that she was pregnant, she changed her mind. Naomi then assumes a new identity and raises her child in the outskirts of Japan, so Kira wouldn't kill both her and her child. That is why her body was never found.

The Finale scene was mostly Bilingual Dialogue.
Near understands Japanese, and the NPA learned English in school and on the job. Enough said. Oh, and the SPK didn't really know what they were saying.

A and B are really...
Alice and Bob of TV Tropes...

Why didn't L just call Batman?
And the whole thing would have been solved in a few days. In fact the finaly episode of the anime would be two episodes of Batman figuring the whole thing out and then twenty minutes of Batman making Light his bitch.

The unnamed Shinigami from Relight is Matt.
Because the Goggles Do Nothing!

When Rem killed L, some of her lifespan was transferred to Light
Rem dies after killing L because she does it to extend Misa's life. But since she's also knowingly extending Light's(keeping him from being outed as Kira and executed), he gets some, too. That's why he gets a Rasputinian Death. He wouldn't have died if Ryuk hadn't written his name down, because of his extended lifespan.

The reason there are so many weird names in Death note

 * The names have been changed to protect the innocent

The unnamed Shinigami is Light, as well as the REST of Kira aswell.
It is entirely possible that after "he" died, Kira became a Shinigami. However, since "Kira" is an identity refering to Light, Misa, Teru Mikami, and that one guy from the Yotsuba Group, the "Kira" Shinigami is reflective of ALL of those people. Since Light was the "brains" behind Kira, he is the dominant basis for the new Shinigami. Light, Misa, Teru, and Pervy all ended up in Mu after they died, but they essentially "live on" through this Shinigami for some reason.

Aiber is A from Wammy's House
A's "suicide" was committed in such a way that the body either wouldn't be found or would appear dead long enough for him to be buried. This allowed him to drop off of Wammy's radar. However, he still wished to beat L and tried to do so by both exceeding his detective skills (while using the name Eraldo Coil) and by being a con-man who L wouldn't be able to catch. Unfortunately, he failed on both fronts, thus losing the right to use the alias "Eraldo Coil" and being forced to either help L when needed or spend a great deal of time in prison. Hence, Aiber uses an "A" to identify himself and is able to act as Eraldo Coil during the Yotsuba arc without anyone noticing any discrepancies between his behavior and Eraldo Coil's known behaviors.
 * This would explain a lot, but L blatantly stated that Coil was another of his aliases, which he was letting Aiber borrow. So it doesn't work.
 * It's hinted in Another Note that L steals the aliases of his vanquished rivals-the names are like his trophies.  So "Coil" could have originally been Aiber's alias and L is letting him "borrow" it back.

The pilot is the REAL Death Note story. Everything else is the manga mentioned at the end of the pilot, making it a story within a story
If THAT isn't enough, Taro is the author of the manga.

The newest Kira is the mastermind the Suicide Club
The Subliminal messages were a red herring. Someone just took advantage of the unlimited pages by making a note system like the one Light used on Ray Penber and making each suicide random.

The American Movie will have Viral Marketing
In the form of ordinary commercials getting interrupted by fake news reels about hostage situations, leading to the offender to collapse from the Death Note. There would also be websites titled "Who is Kira?," "Kira is a menace," "Kira is our savior," etc.