Lost/WMG

Post your fan-theories for  here!

NOTE: The show just ended! For the sake of prosperity, please post any theories either Jossed (proven wrong) or confirmed by season six in the folders labeled... Yeah... Spoilers, obviously.

Past!Ben dies because he got shot.
The island sent Sayid back to 1979 so he would kill Ben, in order to set right the wrongs Ben committed over the course of his life in his deluded attempt to work for Jacob. Sayid succeeded, and now we get to see the fun and games the Island has in store for the survivors.

The hydrogen bomb didn't work.
Instead, the flash of white we saw at the end of the season five finale was a flash like in earlier episodes this season. The flash is considered the incident. Of course, that doesn't mean Juliet and Sayid are any less done for.
 * According to the sixth season premiere, that seems to be true.
 * According to your interpretation of the series finale, this could still be true.
 * What interpretation? Whatever alternate interpretation you apply to what the ending said about the meaning of the flash sideways "timeline", there's nothing open to interpretation about what it means in terms of the bomb: that it went off and the plan didn't work.
 * "Didn't Work" in this case meaning "didn't do what it was supposed to" rather than "didn't go off". Either way, the effect is the same: the flash sideways both does and does not exist.
 * It's pretty clear that the bomb did not go off, and was instead a red herring. If you'll remember, the bomb was only for canceling out the pocket of immense energy. Not just to blow a hole in the island. When Pierre Chang said that the construction workers couldn't even drill a centimeter further over at the Swan station, he really meant it was that unstable. Tons of metal, a hydrogen bomb, and a Juliet falling on the pocket would probably be equivalent to drilling a centimeter. Also, even the warhead of a hydrogen bomb wouldn't just toss Kate into a tree thirty years later. That's island energy. Now that we've seen what releasing all of that energy would do in "The End," it's pretty clear what eventually caused the "alternate" timeline.

The Island will collide with Los Angeles.
If you don't wanna know the title of the season 6 premiere, don't highlight the spoilers.
 * The first episode of the season 6 is titled "LA X". You'll notice there's a space between the "LA" and the "X": that's deliberate. So there's two subjects in that title. The "LA" seems fairly obvious (Los Angeles) but what does "X" refer to?
 * Or maybe the "LA" is Louisiana. Probably not, but it would be even more of a 'gotcha'. Perhaps Lost is crossing over with True Blood as a precursor to HBO buying out ABC
 * The Island moves. That's why the Looking Glass station was built, to locate where the Island will be at a future point in time. The location is indicated by a pendulum that swings across a large map of the Pacific Ocean, and marks the spot with a big white "X".
 * Hence, the theory: the Looking Glass station will draw a big "X" over Los Angeles, indicating that the Island will arrive there at some future point.
 * Jossed by Word of God. The "X" in "LA X" refers to
 * And the station you're thinking of is the Lamp Post, the Looking Glass was the underwater station from the last few episodes of the third season.

The events of the Season 5 Finale will result in one or more cast members pulling a Peggy Sue
Think about it. If the detonation of the nuke was what actually caused the incident, then that means the events of Season 5 were a Shoot the Shaggy Dog, as the characters would have gone through a ton of misery in order to create a stable time loop that will mean they have to go through a ton of misery. On the other hand, if the detonation of the nuke stops the incident, the whole show becomes a Shaggy Dog Story, as nothing ever happened. Therefore, the only way to avoid massive shagginess is for the events of the show to be undone, but for the characters to remember them anyways..
 * Or the writers played the Legacy of Kain series and the bomb is there in the future to be used to save the day.
 * The teasers played at the 2009 San Diego Comic Con are pointing at a Shaggy Dog scenario, at least to start the season off with (Kate not killing her stepdad, Hurley's Mr. Cluck's commercial [having returned from an Australian vacation], Oceanic Air commercial citing a 'perfect safety record'). Not that the writers have ever purposefully misled us before... Right...
 * Even if that * does* happen, the undoing could itself end up being undone or... or who knows what!

Richard is the monster.

 * Let's make the leap that the monster is the Island's way of interacting with humans. We've seen it show up as the smoke creature, which kicks arse and takes names. We've seen it show up in the form of dead people who give out cryptic advice. But what if the Island just feels like having a conversation in a non-threatening way? Richard is the avatar it has created, one that never ages and has been around as long as any of our characters can remember. As Richard, the Island guides the Others and interacts (relatively) peacefully with the other factions who show up.

Jacob is actually Locke
After, Locke is unstuck in time like Desmond. This explains why Jacob is invisible, and he and the cabin seem vaguely intangible and incoporeal. It explains why Locke is able to see Jacob. It explains why, after he grows to accept all the mystic "island wants this" stuff, Jacob/Locke - he was then ready for it. And explains why his consciousness can go back without needing to take over his physical body - he just. Also: take a look at the screengrabs of Jacob, and tell me that doesn't look like Locke's silhouette to you.
 * Check this video out.
 * Jossed during the season 5 finale,
 * Based on the comments the new guys made when they found the cabin it appears that Esau!Locke/Jacob's enemy was the one using it, which explains why he looked like Locke.

Locke is not supposed to replace Ben as the leader of the others. He is Jacobs replacement.
Thats why the Island talks to him directly. It never did that with Ben (or maybe Widmore). He kills/removes Jacob, who wants to quit ("Help me!"), and takes his place. That's also why Ben was not killed by Smokey, who told him to do everything John tells him.

The explosion/incident might have also destroyed the statue.

 * You're probably right about that. Ben tells Sun that he has no idea what happened to the statue, to which Sun replies "Do you expect me to believe that?" and Ben says he doesn't, really, implying that Ben was lying. So the destruction of the statue must have happened some time when Ben was on the island.

== Everyone will die in a huge battle between Jacob and Esau's forces, except for Locke (or Ben, or even Jack), who'll be forced to relive the events of the series for the upteenth time. ==
 * Given Damon Lindeloff and Carlton Cuse's love of Stephen King's The Stand and The Dark Tower, the end of the series will no doubt draw heavily from the conclusions of those two novels.
 * Seriously; Lost already has a disturbing amount of similarities to those books.
 * Season 6 sets off on... drumroll please... February 2nd, Groundhog Day!
 * Picked up by Darlton and explained as a happy coincidence, despite the fact they both want to pretend it was intentional.

No one will leave the island at the end of Season 6.
The idea of leaving has already been explored with the Oceanic Six... it would be anti-climactic to use it again. Those who survive until the end of the story will be stranded permanently on the island due to a change in the mythology.
 * Jossed. The ending shows

Two separate universes were created by
Because the '77 group, there are now two timelines: one in which , and the other in which   Expect crossovers (somehow)
 * Who says the bomb detonated... all we saw was a white flash... like the ones when they time travelled.
 * Basically confirmed as of the season premiere! Score two for crazy fan-theories!
 * ...maybe. There's no evidence to support that the Swan was prevented from being created per se. Much of the original timeline actually depends on the survivors having been in the 70s, such as the possibility of, or Richard remarking to Sun that he saw all the survivors die in the 70s. Some sort of unspecified blast, after which all the survivors time travel and appear to have vanished, conveniently accounts for this. Not to mention that the title "The Incident" rather directly points toward the detonation being the "incident" referenced by Dr. Chang in the orientation film. Assuming that all the 70s events except the bomb detonating did happen seems unnecessary.
 * Is there a world where this was unclear even before Season 6? The Incident was the electromagnetic event that happened before Juliet set off the nuclear explosion. The thing that dragged Juliet into the hole was the Incident. That was clear. It wasn't the detention.
 * What if they're actually the same timeline? See, the bomb worked. Then we have the universe where the plane flies over normally, with people like Jack and Desmond having vague (very vague) memories. But Daniel Farraday set off another bomb. That changed it back to the island, where the castaways only believe the bomb didn't work. Yeah, you need to be a bit crazy to watch this show.
 * Why is this in the "confirmed" folder after the final episode instead of the "jossed" one?
 * Because we haven't had a chance to move it yet. (pause) There we go.
 * Because we haven't had a chance to move it yet. (pause) There we go.

The title of the two-part series finale will be "The Stand"
For several reasons.
 * If it wasn't already obvious by season 6, Stephen King's The Stand was a huge influence on the series' development. Team Darlton freely admit this and claim that a paperback copy of the novel has a permanent home in the Lost writer's room.
 * The sixth season is building to a confrontation between those who oppose the Man in Black and those who follow him: a "stand" against evil, if you will.
 * Because it would be awesome.
 * Jossed. Word of God is that the finale will be titled.

Yet another old classic: The castaways died in the plane crash and are in Purgatory, working off their mortal sins before ascending to a higher plane of existence.
This theory has been repeatedly and explicitly denied by the show's creators. It was also rather heavy-handedly torpedoed by the third season finale, in which
 * Alternative theory: This was where they were going until "The Pilot" aired and everyone said, "Hey, I'm smart, they're in Purgatory!" At this point, the writers promptly went back to the drawing board.
 * Alternative alternative theory: This is all a shared hallucination. They're still on the plane. The last episode will end with them all snapping back to reality, safe in their seats on Flight 815... just as things start to go horribly wrong.
 * Alternative alternative alternative theory: only Locke died. He went to heaven; everyone else just got dragged along for the ride.
 * Alternative alternative alternative alternative theory: they've been dead all along, the entire world is actually Hell, and the island is Purgatory (give them an actual chance at redemption).
 * By the series finale, this was true of the alternate timeline rather than the island.

Christian Shephard on the Island is the monster
It manifested as Yemi to Eko; it's manifesting as Christian to Jack to manipulate him - showing him to the caves, etc.
 * It doesn't explain why Christian appears to Hurley or Michael, though.
 * Confirmed. If you can take Un-Locke at his word (which we just about frigging have to, or risk a serious case of Your Head Asplode) he indicates explicitly to Jack that he, the Monster, was impersonating Christian Shephard in the interests of keeping Jack and the other Losties alive. Conversely, if you take Michael at his word (or, more accurately, Hurley's guess) the appearances of dead people to the living on the Island are usually those of spirits who can't move on. Still leaves open the possibility that Jacob may have been impersonating some of the "dead people" we see, though.
 * Jossed. Christian was an apparition from the afterlife guiding the survivors to their ultimate rest. Unlocke is just a filthy liar.
 * It's clear by the last episode that while The Monster may have appeared as Christian on the Island, at least some of the time, the Christian we saw everywhere else (remember The Monster can't leave the Island) was a ghost, or possibly an angel.

The Adam and Eve skeletons from the caves are either Rose and Bernard or Miles and Charlotte
While bouncing around time, they die about 50 years before the plane crash and are interred in the caves. If they're Miles and Charlotte, they are unable to stop the time bouncing before both die of aneurysms.
 * If it's Rose and Bernard then why didn't they return to the present with everyone else?
 * Since when has "everyone" returned to the present? But this was written before they stopped jumping through time, so is probably not a good guess anymore.
 * The producers said in interview that they hid an anagram giving a hint as to the mystery of the Adam and Eve in an episode wherein the phrase "Only fools are enslaved by time and space" is displayed. This can be re-arranged into "Bones of Nadlers may lay lost deep in cave".

The big twist of Season Six isn't really what we believe it is.

 * The supposed twist of the last season is that there are now But what if these really aren't
 * So Jack has a teenaged son he's literally never mentioned before?
 * No, no. Clearly,

Jacob is actually evil and Esau is good.

 * The Others are really on the side of Esau- not Jacob.
 * Jacob is the 'darkness' that has 'claimed' Sayid. Esau had been trapped in the cabin until the ash was disturbed so that he could not foil Jacob's plan of bringing "them" to the island.
 * Jacob was always in favor of outsiders coming to the island, yet all the Other/Hostiles ever want to do is kill or capture anyone who comes.

The final episode of Lost will be a rebroadcast of the final episode of The Prisoner
...and J.J. Abrams will never stop laughing.

Past!Ben survived getting shot
Everything up to this point has suggested that Lost uses the "one unchanging timeline" model of time travel, which means that since we have seen Ben as an adult, he can't die as a child. Plus, the island's healing power could save someone from that kind of injury, e.g. Locke at the end of season three.
 * Why do people say "everything has suggested this" while conveniently forgetting Desmond suddenly remembering that Daniel Faraday contacted him 3.5+ years prior to his 'dream' telling him to find Faraday's mother. "But Desmond is special" people say... my butt.
 * Or maybe in their return to the island, they have created a separate timeline in which, I dunno, Past!Ben could die while Ben could still live, unaltered. I dunno. Time travel is screwy.
 * If time travel caused the past to change, then Desmond would not have suddenly remembered stuff that happened 3 years ago, he would have always remembered it in the new timeline. The sudden recollection suggests that he is unstuck and not experiencing time in a linear sense, which is, you know, explicitly stated to be what is happening to him.

Charlotte/Faraday's mother is .
In the season 5 premiere, both characters have potentially important lines relating to their mother. Charlotte says that she briefly forgot her mother's maiden name, which seems like a trivial thing to randomly forget. Faraday, when he meets up with Desmond, tells him to go to Oxford and find his mother. At the end of "The Lie," Like mother like son? Also, in the fourth season, Charlotte makes a statement to Daniel stating that she's still looking for her place of birth. Whether or not this links her to is unclear, but it might link her to the island itself, Dharma, or the Others.
 * As of season 5 episode 5,.

Jacob's enemy is the monster
The monster is Jacob's enemy, the dude in black shirt who doesn't want people to come to the island. It's fairly obvious he can shapeshift, he's taken on Locke's image in order to get rid of Jacob. My guess is his true form is the black smoke, he just shapeshifts into a black shirted guy when he wants to appear human. Jacob, on the other hand, wears a white shirt. Remember Locke describing his first encounter with the monster? That he didn't see black smoke but rather a white light? That's because he wasn't looking at the monster, he was looking at Jacob's true form. Black and white. Get it?

The monster is
We know the monster can take the form of dead people, particularly those who come in contact with the island. It manipulated the situation so that. It then manipulates Ben, both as and as Ben's daughter in order to find the "loophole" it needed to kill Jacob.
 * Makes sense. After all, when Ben met Cerberus/Smokey.
 * Also, when Ben calls the monster, it's that shows up, with Smokey nowhere to be seen.

Desmond can jump between the two timelines
In the non-crash timeline shown in season six episode one, Desmond was on the plane sitting next to Jack. This is despite the fact that in the original timeline he was already on the island at this point. Now, OK the destruction of the island would cause his life to change significantly, but it's still a bizarre coincidence that he just happened to end up on exactly the same plane as the rest of the cast. On the other hand if he knows about the split timelines then he could have got on flight 815 deliberately in order to meet up with the castaways and set up some sort of long-term plan. The reason why he didn't tell Jack anything at the time is that explaining five seasons of Lost to a complete stranger is a good way to get yourself committed.
 * For further evidence of this, look all the way back to Flashes Before Your Eyes, the very first time travel episode in season three. Desmond jumped back a few years, but the things he saw were subtly different from his memories (the football game ended differently, the angry guy came into the pub later than originally and ended up hitting Desmond instead of the bartender, and Mrs. Hawking appeared and pressured him into following his original fate). This made little sense at the time and got worse when we started to hear about "Whatever happened, happened", but if he was actually in another timeline at the... time, then the minor changes could have been from the butterfly effect and Mrs. Hawking may be trying to merge the timelines.

Jack's going to become Jacob's replacement.
This part has been confirmed in the penultimate episode, "What They Died For", but I don't know if the rest of my guess will be. The rest of my guess is:
 * And then, once the smoke monster is again sealed (or whatever), he's going to revive . Or maybe...

Juliet is the mother of Jack's son in AU
Well, we hadn't seen the boy's mother yet. We heard how Jack spoke with that woman on the phone but she wasn't shown. This can mean that she is well-known character from original timeline. And except for Juliet,we already saw all known female heroes in AU. To be honest, I wasn't sure if it was Juliet or Anna Lycia... until we met Anna.

The reason why Desmond is taking Kate to the concert
Is because he wants her to remember the events of original timeline. Love and pain are the only ways to achieve it, well, Jack is gonna be there too...

Desmond can enter the Source (or the Light, or whatever we're calling it) without being harmed.

 * That's why he's so important. His ability to withstand severe electromagnetic anomalies (i.e. this by-product of the Source affecting the real world) means that if he were to go into the Source, he'd be perfectly fine, as opposed to the Man in Black, who went into the Source and turned into the Smoke Monster (and it's implied that their Mother did the same thing).
 * The same thought has occurred to me. Don't know whether it'll turn out to be true or not, but I have definitely thought it plausible.

Desmond will help
The Man in Black wanted  The question is why. Why would this be the crack in MiB]'s armor? spoiler:A bit off the wall here, but what if Desmond is like a battery (or a Pikachu, perhaps) and is unknowingly storing all that electromagnetism inside him? Perhaps electromagnetism will hold the same properties that the sonar fence has again [=MiB ?
 * Confirmed--sorta.

Hurley will become the new leader of the Others

 * He often has sudden insight and is sensitive to undead visitations. He is more astute than he gets credit for (even from himself). Locke was deluded (as shown by the events of season 5) to believe that he was special, but in fact the special one has been Hurley all along.
 * Sarcastically confirmed in "What Kate Does" by Miles.
 * And now confirmed, in a way, by the show itself in the final episode. Hurley became Jacob's (and ultimately, Jack's) replacement, with Ben as his second-in-command.

Lapidus is still alive.
I have no in-story evidence, but it makes sense from a production standpoint for two reason.
 * We don't see him die, nor do we see his body. We very deliberately do not see either of those things. More than likely, the idea is more to have the characters believe he's dead.
 * With the submarine destroyed, the only way off the Island is via the Ajira plane. So if the writers plan to have anyone get off the Island, it's gonna have to be on the plane, which is gonna need a pilot, and the only pilot is Lapidus.

The show will end with a Gainax Ending
Its the only way it can end.
 * And in a way, it did. As in, the finale is very similar to the series ending of NGE, isn't it? (Also, it was pretty weird even for this show.)

Richard is immortal
He appears in multiple decades and is the same age each time. There was a good deal of speculation that the Dharma project was, in fact, immortality. Richard is their proof-of-concept.
 * But Richard visits Locke as a child back in the 1950s, twenty-odd years before Dharma was started. The theory still holds water because we don't really know all about how the time travel works yet, and that could go towards explaining it.
 * Ricardus is more likely from the Black Rock.
 * Confirmed on all counts ...

There will be a movie called End of Lost.
Everyone will get hugged and turned into tang.
 * Surprisingly close. There was a movie-length episode called "The End", where everyone got hugged.

Exactly what happened inside that cave.
EDIT:
 * There seems to be a lot of confusion over exactly how  and it has even gone so far as to lead many to say that the two characters are not one and the same after all, even though the podcasts, the info on the "enhanced" versions, and the show's own dialogue have all confirmed it. Well, it seems fairly obvious to me, at least upon a single moment's reflection, that what happened is this:

An old classic: All the weirdness on the island is due to the fact that some of the trees suffer from epilepsy
Hey, why not?
 * Some of them were transplanted from the Old Forest.

Another old classic, for old times sake: Ethan Rom is The Devil.

 * And Ethan/Devil is also the Monster. And the Polar Bear. And Jack's dad. And... yeah.

The island is an Age of Myst

 * Mysterious underground areas with ancient technology in them? Other mysterious underground areas with more modern technology in them? Animal life that may or may not necessarily belong there? People who find themselves in a bizarre setting exploring the remains of various groups that had gone through previously, and trying to slowly piece together what had happened? Sooner or later Atrus will show up and explain everything; all that's missing is a Linking Book taking them to yet another island. Maybe they're saving that for the zombie season?
 * According to Wikipedia Myst was one of the inspirations for the show.

The flight's number is a Tintin reference.

 * Lost is about Flight 815. There is a Tintin book called "Flight 714". 8-1=7 and 15-1=14.

The Island is Fantasy Island.

 * Left without the creator/shaper of the island, the piece of land was left to amuse itself, and now fulfills wishes or nightmares as it pleases. The mroe powerful the person (like Locke) the more likely the Island is to obey you.

John Locke is reincarnated as Charlie the Unicorn

 * "Aw, they took my freakin' kidney!"

One or more of the characters is a Time Lord.

 * This troper votes for Charlie. He's the resident Brit, and he can't die. It was only a flesh wound. He'll regenerate. The only reason he hasn't done so yet is he's in a perpetual state of drowning.
 * As per the recent episodes, This troper wishes to expand this particular WMG to "Massive EM Field exposure has turned Desmond into a Time Lord."
 * Can't we have one fricking page on this whole site without someone speculating that such-and-such is a time lord??!!
 * Here you go.

Jacob and the Others are the good guys; Esau and the Losties are the bad guys.

 * The big assumption is that Jacob is a goodie and Esau (or the Nemesis, or whatever you wanna call him) is the baddie. Based on their conversation at the beginning of "The Incident", I'm gonna say that yeah, Esau = bad.
 * The other big assumption is that Esau is Smokey the Monster. I'm calling this based on stuff in S5, when the Monster and Esau are explicitly not shown together.
 * The Others work for Jacob.
 * Jacob's goal is the preserve the Island, an Eden-like place where everything is plentiful and people can be cured of any injury or disease.
 * Uh, maybe it * was* at some point, but now it's at least as much a deadly location full of monsters, maniacs, and polar bears. You could say that this was the result of some fall (those corpses were dubbed "Adam and Eve") yet if Jacob is trying to * preserve* the Eden-like quality of the place then he wouldn't be leading the group which presumably made the spot so much more un-Eden-like.
 * The Losties, from as early as the fifth episode of season 1, are manipulated by visions of dead people. It's implied in an early season 3 episode, and confirmed in a season 5 episode, that these visions are, in fact, the Monster taking on the appearance and mannerisms of the dead people (this adds credibility to the theory that Esau is the Monster, since Esau spent half of season 5 in the form of a dead person).
 * Esau's goal is the destruction of the Island--more specifically, his goal is to expose the Island's existence, bring people to it and make people destroy the Island.
 * I don't know if that's true or not but he does indeed seem to need the help of an external party to destroy Jacob, at least.
 * Jacob and Esau are playing some kind of game, with rules and loopholes. If you think of it like chess, then Jacob's pieces are the Others, while Esau's pieces are the Losties.
 * Esau is cheating; he's turned the leader of the Others, Ben, into one of his pieces. Events in season 5 indicate that Esau was the one who healed Ben when he was shot as a boy, and at that time Esau exerted his influence over Ben. Additionally, Ben seemed to think that Jacob was the individual in the cabin--an individual who appeared as Christian Shepard, a dead man.
 * Furthermore, Esau's influence over Ben likely led to him excommunicating Charles Widmore from the Others, which in turn led to Widmore sending the freighter to the Island and trying to kill everyone on it.
 * It's likely that Jacob is also cheating, by leaving the Island and meeting--specifically making some kind of physical contact--with a whole bunch of the Losties.
 * Jacob also seems to have cultivated a faction that works off the Island (the "what lies in the shadow of the statue?" group) on his behalf, the equivalent of how Charles Widmore works for Esau off the Island (though without realising this).
 * Jossed on many counts; The 815 survivors were Jacob's chosen, Widmore is apparently on Jacob's side, The monster believes that Humans Are Bastards, with Jacob taking a more optimistic stance. The monster leaving the island could destroy the world, and he's proving to be little more than a violent, Manipulative Bastard.
 * By the end, it's still not clear exactly who were the straight-up no-chaser good guys. This is a series that runs on Grey and Grey Morality.

John Locke is the anti-Christ
So, here we have a man who, through the use of time travel and Magnificent Bastardry, comes to an island fully believing he is "special". Lo and behold,  That war and extreme misfortune seemed to follow the man around before that solidifies him as the red rider of the Apocalypse.

The island (or part of the island) is the remains of an alien spacecraft
The whole thing can  Come on. Aliens either seeded life on Earth (which began on the island...four-toed statue, people, surely that's of a "proto-human"), or experimented on a specific group. IT ALL MAKES SENSE!
 * The Ancients built it. The Others are their descendants, who gradually de-evolved because they lost technology and with it their history.
 * Building off of that, The Monster  is a partially-descended (similar to Anubis) human.
 * Jossed. He's a human being (Jacob's brother), specifically, or at least was until
 * Jacob and Nemesis/Esau/ are aliens sent to Earth for some kind of an experiment. The pocket of electromagnetic energy is the core of the ship, and the frozen wheel is a piece of it's technology. In LA X, This would also fit in with Jacob and Nemesis' conversation by the statue.
 * And, building off of that:

The Island is Gallifreyan.

 * It's either Time Lord technology or a piece of Gallifrey that ended up on Earth after it "burned" in the Time War. The pocket of electromagnetic energy/the frozen wheel could be a kind of pre-TARDIS time-traveling technology. In the season 3 finale of Doctor Who we see that time-travel without a capsule really isn't a good idea. This would explain why the LOST time-travel tends to kill people, especially if the teechnology is pre-TARDIS.
 * Adding onto that, Jacob and Nemesis are Time Lords who escaped the Time War, probably through the use of a Chameleon Arch like . Also,
 * Richard Alpert said that Jacob made him what we're calling 'immortal'. What if Richard was a human who became Gallifreyan using some kind of Chameleon Arch technology? Gallireyans apparently age very slowly, which would explain why Richard always looks the same- no one's tried to kill him and he hasn't had to regenerate from old age yet.
 * This one is Jossed. However, we don't know whether Jacob & MIB's mother was Gallifreyan. If so, she must have been out of regenerations.

Jack Shephard is the brother/half-brother of Derek Shepherd

 * And they're both Jesus. Healers called "Shepherd"? Come on!
 * Hell, in the space of one week,

The Island is all that remains of an ancient Mu-like continent
Previously home to a pre-human civilization. Hence the giant four-toed statue.
 * This jibes well with the moving island, since the continent of Mu is variously described as being in the Atlantic, Pacific and other oceans.

The castaways are actually on the set of a wildly successful TV programme, the Creators of which have absolutely no idea what they're doing and just make everything up as they go along.
Lost is a wildly successful TV programme, whose creators have absolutely no idea what they're doing and just make everything up as they go along.
 * To make decisions on "what will happen next", they brainstorm a bunch of options, then look at all of the forums out there with pet theories, and choose the one option on their list that wasn't mentioned on the forums.

The Island is Gilligan's Island
And Neverland. And Skull Island. And the Island of Doctor Moreau. And the Island from The Prisoner. And Nomanisan from The Incredibles, with the monster being another Omnidroid prototype. And Avalon from Arthurian mythology. Seriously, how many uncharted islands can there be on Earth? ""Bali Ha'i may call you,
 * Alternately, it's not on Earth, but in the Avatarverse, in the ocean that makes up a huge part of the other side of the planet.
 * Alternately, the Island is somewhere on the Grand Line.
 * Alternately, the Island is Bali Ha'i. "We have to go back", anyone?

Any night, any day

Here am I, your special island

Come away, come away.""

Ben Linus is an Author Avatar for Darlton.

 * Think about it: both have no clear motivations, both refuse to give straight answers even under torture, and both are experts in screwing with people. IT MAKES PERFECT SENSE.

The Beast is the Uluu Thalongh from Dungeons & Dragons' Forgotten Realms Campaign Setting.

 * "Of all the legends whispered about the monster-infested, swamp-riddled jungles of Chult, the most eerie is that of the Uluu Thalongh, a name whose meaning has been lost along with the tribe that bestowed it." â€”Forgotten Realms Manual, p. 107.
 * The Uluu Thalongh is a highly mysterious... something... that controls plants, imitates voices, and eats people. It's impossible to kill. It can appear out of nowhere. It's found in the jungle. No one has the faintest idea what it is.

Ben is "unstuck" like Desmond; the difference is that he knows how to control it
Ben has the ability to routinely pull off Gambit Roulettes that clearly should rely on large amounts of luck, to the point that he seems downright omniscient at times. He obviously has some kind of edge that we haven't been told about, and controlled time-travel would be able to give him one; since he's lived on the island for most of his life, a "constant" shouldn't be hard for him to find. Basically, he could try a plan, see where it went wrong, and then go back in time and act in such a way as to avoid any dangers, a bit like loading an old saved game whenever you screw up.
 * What about the part in season 4 where ?
 * That may have just been because Widmore 'changed the rules' to alter the time stream in some way.
 * What about the part in season 4 where Ben is trying to get Juliet to love him and all of his attempts fail? Also, Faraday plainly states in season 5 that you can't alter the past when traveling through time.
 * Come on, we know his constant! It's the wooden figurine he got from the sweet girl when he was a kid!

Lost and Cloverfield take place in the same continuity.
Not an original theory, but it's been tossed around the Internet enough to warrant a mention here. See the "Cloverfield" Wild Mass Guessing page for more on this.
 * There have been a few very subtle crossovers between Lost, Cloverfield, and Heroes. Anyone for Slusho?
 * The theory that Cloverfield is the One-Winged Angel form of Ben Linus is awesome.

Libby's husband is Desmond from another time.
Libby's last name is left deliberately unknown for no good reason. She calls her husband "David," which is also Desmond's middle name. Going back in time to indirectly give himself the boat Elizabeth helps Desmond mend things with Penny and also save the island.
 * Not bad.
 * In the season 6 alternate timeline Desmond is married to someone, but it's unlikely to be Penny

It's all about the authors vs the islanders.
The ending is going to be one of those Stephen King-style meta-things in which the islanders turn out to be characters in the TV Show Lost and all the dark and mysterious opponents are agents of the authors. The final battle will be between the authors and the characters for the control of the series. The characters will win. There are various clues pointing to this ending. Hopefully they're wrong, though, because, well, ewwww.

The entire show was invented to drive people who read a lot crazy
Come on: It has obscure background motifs, prominent mathematical ones, references to Hindu doctrine, heavy mythological symbolism, at least two characters named after Enlightenment-era philosophers, Misplaced Wildlife on an epic scale... Clearly, we are intended to blow out our minds trying to figure out what the hell is going on, leaving the world clear for a coup. And we, as Tropers... will be first.
 * That assumes any of us were sane to begin with.
 * I AM THE LIZARD QUEEEEEEEEN!

The castaways are brainwashed actors
All the castaways were originally actors hired to play the various characters in the then still-in-development TV show Lost. Once they had learned all their lines for all the seasons, they were brainwashed, and the entire script was planted into their subconscious. They were then stranded on the island in question (the plane crash was a controlled crash via autopilot) and started acting out their parts simply because it was all they knew. By the same token, the flashbacks and flashforwards are experienced by everyone via simultaneous blackouts; however, only those whom the script says are having any particular flashback remember it, in a similar fashion to remembering (or forgetting) dreams. It also explains why Ben can pull off Gambit Roulettes and why the weirdness on the island hasn't driven anyone insane yet: it's all in the script! As for the mysterious healing powers of the island, that's simply because the ACTORS never had the injuries/illnesses in question; they just thought they did.

Lost is an unintentional companion piece to Battlestar Galactica
And the Island is the cause of the time loop in that series.
 * Taking a step further, the two series are part of the same universe and The Others are all Cylons. Or at least Richard is.
 * Jossed; Hurley asked Richard point-blank if he was a robot and he said no.

The Island is an Adventure Game
Jack is playing. It begins, "You awaken staring up at palm trees. A labrador retriever is nearby." When he types good questions, the computer responds, "I don't know how to what is the monster."
 * This is my personal favorite Lost-related theory of all, although I don't think it very likely and I'm still not at all sure that whoever posted it didn't mean it as a joke. I just think it's awesome.

Libby is an American Widmore
A few things:
 * Her last name wouldn't be so secret if it wouldn't blow our minds.
 * There is, according to a semi-canonical tie-in novel, an American branch and a British branch of the Widmores.
 * Isn't it convenient how Widmore-- wait. NO. NO. See below.
 * Wouldn't it be convenient if a Widmore gave Desmond a boat?

Charles Widmore led Desmond to the Island so Penny would find it.
Come on, so far he's eefused to let Desmond marry Penny, which Ms. Hawking said would lead Desmond to the Island. He's gone to great lengths to keep Desmond and Penny apart, fearing that Desmond would not go to the Island if he went to Penny after prison. But when Desmond needs to talk to Penny to set up the phone call in "The Constant", Charles is quite helpful.

Ramsey Street from Neighbours is on The Island
Think about it--Ramsey Street seems to have crazy healing powers where paralysed people end up walking again in a few months, blindness is only ever temporary, and donating a kidney will have you out of hospital in a day. Seeming death on The Island or on Ramsay St is not the same as real death: instead, you will end up back in the "real world". This happened to a native Islander known as Jim Robinson, who desperately wants to return to his homeland. Shoring up lots of cash and changing his name to Charles Widmore, he embarks on a frantic quest to return. This would also explain why Hurley sees Charlie and Mr Eko; he's not mad at all. They're just there.

The show was SUPPOSED TO BE Too Good to Last
Think about it. A huge cast of characters with a large number of secrets, stranded on an island. Gradually, this is revealed to be a set-up for a complex Myth Arc. It's amazing that the show drew such a huge audience. The assumption was probably that they'd draw a small but devoted fanbase and then cancel after half a season with an amazing set-up but nothing explained - like Day Break or Journeyman. The fans would then buy loads of DVDs and merchandise in an effort to bring the show back, while spouting theories, and the producers would swim in their money. When the show caught on, they were totally unprepared and have had to wing-it ever since. It was Springtime for Hitler, TV exec style.
 * Technically true. As far back as 2007, the show's producers were saying that it was intended to have a beginning, a middle, and an end. The conclusion in 2010 has been planned for at least three years.
 * Confirmed by Word of God -- sorta. While working on the pilot with JJ Abrams, Damon Lindelof was sure the series wouldn't go further than 13 episodes, and it'd just wind up being one of those awesome DVD collectables. That's why there wasn't a solid idea of the series' mythology or plot structure in season 1, just vague notions of where the show might go and what the answers to the mysteries might be. Then it got popular, Abrams left the show, Darlton took over, they mapped out most of the show's mythology and plot structure, and the rest is history.

The Island is just a regular island; there's no magic, monsters, or time travel
All the fantastic elements are there solely because of an Unreliable Narrator - in fact, they only exist in the heads of the characters, who are slowly descending into hallucinatory madness due to isolation and harsh conditions.

Hurley is still insane.
Everything is happening inside his mind. Also, that guy who turned out to be imaginary ISN'T, and Hurley would have somehow become sane if he had jumped off the cliff with the guy. Either that, or he would have died after jumping off the cliff, and the series would have ended.
 * An expansion of this: Hurley is still in the mental hospital and having a hallucination. Everyone he's ever met since 815 crashed - 815ers, Others, Freighties, The Dharma Initiative and assorted characters like Rousseau, Penny and Desmond - are all patients, staff or visitors at the mental hospital.

The island is a peninsula
After all, there are many parts the Lostaways never found.
 * Haven't we seen the island from the air? It didn't look like a peninsula then.

The series takes place before 9-11; the plane was hijacked...
Hijacked by the Others. Boone didn't die from a fall; he was thrown off the top and died from his injuries hitting the tarmac. Shannon was shot as an example to the police surrounding the plane.

The four-toed statue is a statue of .
This theory is on Game FAQs, and it's just too perfect. In the season 5 premiere, Therefore,   to inspire a statue to be built of him.
 * Given what the rest of the statue is revealed to look like at the end of Season 5, then Sawyer's appearance through the years has been... embellished a little.

The island is all an experiment run by the Voorlons.
They want to make sure humans will be able to fulfill their destiny when the time comes. Whether Rousseau is Delenn or just some relative isn't that big of a deal.
 * She the person who's DNA the used to make Delenn more human.

The island is an alien turtle
Everything takes place on its back, and the smoke monster is its immune system (which has somehow become sentient). Whenever a dead life form arrives on the island, or whenever someone dies on the island, the smoke monster absorbs their consciousness, allowing it to project them as living beings. It's even able to project them in locations other than the island. As for the time-travel and the time-teleportation, it's an ALIEN turtle which has this ability for no reason whatsoever. The creature is able to project its mind, and the projection is known as Jacob. The thing can only project its mind into the minds of certain people, explaining why not everyone can see Jacob or his cabin. That explains quite a bit. Oh, and just to be clear, this is an alternative to the island being an alien spacecraft... especially if the turtle can travel through space.
 * And if it has four elephants and a disc on its back.

Walter Bishop (from Fringe) was part of the DHARMA Initiative.
Come on! What else could his "Fringe Science" be?

Charlie is... Charlie.
Penny and Desmond's baby, supposedly named after Charlie Pace, is the original Charlie Pace. Somehow, he will become involved in a stable time loop and leave the island in the past, grow up, and one day get on the plane and return to the island, where he will reveal to his father, Desmond, that the boat does not belong to his mother.
 * Or maybe baby Charlie is Charles Widmore as an infant. At some point, he gets adopted (most likely by the Others) in the past, so he does not recognize Desmond as his own father.
 * It's possible that all Charlie, Charlie, and Charles are all one and the same, either through some sort of unstuck time manipulation (has it yet been claimed that meeting yourself in the past is bad? Is there any indication you can't exist twice in the same time?) or, more likely, reincarnation.

The entire series is part of a complex stable time loop
Just all the the main characters end up in the distant past and become the ancestors of the Others, with Jack becoming Jacob. One of their offspring leaves the island to found the Dharma Initiative, which ultimately leads to the electromagnetic pulse that causes Ocean 815 to crash. If the current Ocean 6 do not return to the island, they will create a paradox that will destroy the entire universe.

The Island is a Magnificent Bastard.
The Island is not just a place where weird things happen. It is, for some as of yet unexplainable reason, a sentient and bitter entity with near god-like powers that is purposefully orchestrating events to further its own agenda. Jacob, the whispers, the smoke monster, ghosts, and most other phenomena are all extensions of its power. It is unable to directly work against free will, but it uses these elements to fracture the psyches of the islanders and castaways and push them toward doing its bidding. It used its far-reaching influence to damage Oceanic 815's communications, which led it to the area near the island, where events in the hatch brought the plane down, and then protected the passengers who seemed conflicted and had troubled pasts that could be manipulated but let the others who could possibly interfere in the future die. The Island is actively working against anyone who has found resolution and peace in their lives - either working to unravel them again, using whispers and ghosts, or ending them after they've outlived their usefulness or become resistant. The Island is also working to make all lovers star-crossed to keep them from becoming resistant to its power, so they will continue to do its bidding. The "destiny" and "course correction" are a part of the Island's powers, possibly working against actual destiny. Charlie was truly destined to push the button, and "course correction" was the Island plotting to kill him. Desmond is, for whatever reason, immune to the island's will and power, and his visions were the result of actual destiny. Additionally, Charlie drowned because he blocked himself off from Desmond; the island altered the physics of the station to flood the entire room out of revenge and because it could then use visions of Charlie to manipulate others, namely Hurley, later. Mr. Eko scared the island or was so influential that the island decided to let him live in the hopes that it could eventually gain control over him. He understood what the island was, though, and realized its plan, and purposefully did the opposite of what the island wanted when he saw Yemi, and died rather than fall to the island's influence. The Island was healing those who would be more vulnerable to it when miraculously healed. Shannon's asthma was not healed, so Boone could become conflicted and malleable. The Island also orchestrated her death, letting multiple people hear the whispers and making Cindy disappear to make trigger-happy Ana Lucia panic and shoot Shannon. Ben got sick because he was becoming a manipulator and Magnificent Bastard in his own right, no longer believing in Jacob or destiny, and getting into a land dispute with Charles Widmore over the Island, each having the audacity to believe the island belonged to them and not vice versa.
 * Furthermore, Locke is very happy, as he is "special" here, and regarded with respect by the Others... but his mother called him special as well, if only to use him. The Island is also playing Locke, making him out to be special, only to control him. He's always been naive, so the Island "sensed" this in him and decided he would be easiest to manipulate. Once he runs out of usefulness, expect a quick and ironic death to follow. Wouldn't it really fit his character development?

The Island is located in the Deep Wyld of Exalted
Well, it explains pretty much everything and a little more...

The series is actually a DC Elseworlds title adapted to television. The characters have been stripped of all copyrighted and trademarked names and insignias to avoid a lawsuit

 * Jack is Superman. Since in this universe no one (or very few people) have powers he fulfills his urge to save people through medicine.
 * Kate is either Lois or Wonderwoman simply by virtue of being the female (leaning towards WW since she does kick some butt on occasion)
 * Catwoman? They look more alike, and the criminal mindset works. Ben cannot be Batman.
 * Ben is either Luthor or Bruce Wayne. It's not quite apparent if he is a good guy or a bad guy and he always seems like the most 'in the know' guy in the room.
 * More likely, Sawyer is Bruce Wayne. Lost his parents to a petty criminal (conman drove them to murder/suicide), studied their methods (became a con man) and he's been holding that grudge for a pretty long time. Also, has a strange rivalry with Jack/Superman. And, as demonstrated, he knows how to pull off Batman Gambits!
 * Hurley is...crap, I don't know. Help me out here folks!
 * Matter-Eater Lad?
 * Plastic Man?
 * Beast Boy?
 * Charlie's the Flash.

The Island is Tasmania.
I mean, come on. Unexplained phenomenon? Four-toed people? Excessive violence? Everyone wants to leave and never return? Tasmania all over. The plane could've taken a slow right-hand turn after leaving Sydney and crashed. If they walk far enough, the Losties will probably stumble onto Hobart sooner or later.

The island was epileptic, and the trees were rooted in the space-time continuum.
That's how all this time travel stuff works. The shaking trees were really grounded to the proper place and time, and a bubble of space around the island moves around, using the trees as an anchor and casting-off point.

Abaddon is Walt
Walt made repeated mysterious appearances in early seasons and in one case was specifically said to look taller, plus he has shown signs of precognition which could well be a mild form of mental time travel with him "remembering" the future. Then we've got Abaddon, a mysterious figure with the same skin and eye colour as Walt, who seems to know a lot about the Losties and whose origins and motivations are almost completely unknown. At some point in the future Walt will travel back to the island, end up several decades in the past, and grow up to be Abaddon.

Jacob is Anubis
Think about it. He has supernatural powers, manipulates the dead, and as of a recent episode, may also have a statue of himself built on the coast. Considering the rest of the Egyptian themes in the show, would it really be that far of a stretch?
 * Seeing that the statue he lived in was of Tawaret, that might be a better suited Egyptian god for him.
 * Anubis actually seems likely, since the Tunnels had a carving of Anubis facing the monster, and.
 * We never really get an answer as to why there's so much Egyptian iconography on the Island, but perhaps some people from Egypt came to the Island and assumed Jacob was the human incarnation of Anubis/Tawaret?
 * The Egyptian presence on the island was presumably at least several centuries before Jacob's Roman mother arrived.

The LOST Numbers, collectively, equate to Numberwang!
In the Mitchell and Webb Look sketch "The History of Numberwang" the WW 2 professors insert the LOST Numbers (4 8 15 16 23 42 but in the format 4 8 15 162 3420) in a special computer which calculates that they are in fact Numberwang!

Everyone is hallucinating everything.
The plane did crash, but it was somewhere in civilization. Everyone is in a coma, and when someone dies in the show, they either wake up or actually die. The Oceanic Six woke up, but Jack wants to get back into the hallucination, which is why he keeps flying- he wants the plane to crash so he can start hallucinating again.

The Island is or contains The Garden of Eden
And the smoke monster is the "angel with a fiery sword" guarding it.

The Island is Atlantis! Hey, why not?
Atlantis didn't sink; someone just turned the wheel underneath the Orchid. (At least, where the Orchid would later be built.)
 * As of Season Six, this is strangely plausible, since

The Island is a part of the Shivering Isles.
Jacob is Sheogorath. He has a beard and everything! Naturally, this also means Locke is his Champion and Richard is Haskill.
 * Obviously, this new business about  is all about stopping the   and Ben is going to end up as a Priest of Order. Locke will

The Island is the American government's version of The Village from The Prisoner
The Dharma Initiative was getting it ready in anticipation of burning agents once the Cold War was over but the constant time shifting made it that prospect unattractive. == The Dharma Initiative originally formed some time in the 1990s-2000s as a group of time travellers dedicated to preventing the tv series Dharma and Gregfrom ever happening (thus saving the world). == They clearly failed in that mission.
 * Because they lacked Desmond the first time around. But now that they know that...

The Island is a non-sentient black hole of Fate.

 * Nobody's responsible for anything. Ben loves this place.
 * For an unknown reason, the Island's weird geographical (and magnetical, electrical, psychological, terrestrial...) phenomena caused it to gradually draw people to the Island way back when, when it snagged a bunch of Egyptians. A thousand or so years later, it snags the Brothers Grim. Then the process begins to accelerate with the arrival of the Black Rock. The more people drawn to the Island, the stronger its influence and the faster the rate at which people get sucked in. The Others arrived at least a hundred years before the Losties, the Dharma Initiative thirty, the balloon and plane roughly ten to fifteen, Desmond three, and with the arrival of Flight 815 the process practically motors along with everyone and their grandma turning up. The Island is just gearing uo for the stage where it swallows everyone and everything in existence. * SLLLLLUUUUUUURRRRRP* !

The Incident was never supposed to happen.

 * After spending the better part of the season inundating viewers with "You can't change the past; whatever happened, happened", Daniel suddenly decides that maybe he can change the past if he tries hard enough (The Variable).
 * The first time time travel was brought up in Lost (Flashes Before Your Eyes), we were told (by Daniel's mother) that -- it's not that you can't change what happens, it's that "The universe has a way of course-correcting itself" So The Incident was never supposed to happen, and the events of Lost are the universe's attempts to Set Right What Once Went Wrong.
 * Possibly supported by Daniel's statement that Jack was never supposed to go back in time, and the fact that the writers on Lost are big fans of Half Life. "The right man in the wrong place (or the wrong time) can make all the difference in the world."

The characters aren't having flashbacks/forwards, they're physically reliving the events through time travel.

 * Obviously whatever property of the island that is caused Desmond's time travelling is also affecting the other main characters, but to a lesser extent, explaining why they cannot remember the trip afterwards. Desmond's premonitions/time travel are just a side effect of whatever happened to him in the hatch allowing him to remember his trips forward and backwards as well as remembering his present, on the island, timeline. The fact he can remember everything that's happened to him up to being on the island that lets him attempt to change the past, for example choosing to buy an engagement ring that had opted not to buy the first time around. The other characters trips play out as flashbacks as they don't remember anything that happens after the event and so without a new frame of reference would make the same decisions or mistakes all over again.

The island is taking place on a set similar to that of The Truman Show.
All of the islanders are involuntary actors on a giant TV set (except, perhaps, those who died), and all of the events are controlled by TV executives.

Pierre Chang will reveal his middle name to be Francis.
Then he will open a chain restaurant...

Juliet was able to
Of all the flashbacks in "The Incident", only Juliet's  Everyone else, meanwhile, somehow   Perhaps this was somehow supposed to lock them into their destiny and what would have normally preceded:   Maybe Juliet is  ...somehow.

Whatever Happened, Happened really does hold
As Miles said in the finale,. Our Losties cause The Incident.
 * Then how did
 * It was at the bottom of a deep hole with a mysterious energy field, and burying it was the original plan to keep it safe. It's not too hard to handwave away that the radiation levels were low enough to be survivable.
 * Besides, it's a tropical island with polar bears. Realism isn't an issue here. Did I mention the polar bears? With, y'know, dark skin and clear fur explicitly designed to trap heat? On a muggy, hot, sweaty tropical island?
 * Further evidence that we're still in the same timeline are the Adam and Eve skeletons from season 1. The writers have claimed that these were put in so that at the end they will have evidence that the main plot was planned from the start. It makes very little sense to explain this in flashback, especially if the main characters have never visited the island, so the origin of the skeletons must come in the characters' subjective futures. But if history really has been changed then nothing anyone does can possibly lead to the events of the erased first five seasons.
 * Also, it wasn't a complete

The Island is Zeta Point after a lot of time passed.
Both appear to be tropical islands that can travel through time and space. After several hundred years, Zeta Point ended up becoming dilapidated and nearly abandoned, the Others found it and assumed that the future technology was in fact magical and ended up colonizing the Island. Jacob are presumably decedents of the original Alpha Gang.

Calvin Ball
'nuff said - Jacob and his rival are playing a match of it.
 * No wonder Ben's confused.

Good versus Evil or something else?
Wasn't Jacob cooking a Red Herring at the beginning of the season 5 finale? Coincidence, smug joke by the writers to fool us fans... or maybe a real clue about Jacob's true nature?. An Order Versus Chaos conflict or a Grey and Gray Morality situation could potentially be more interesting than a simple "One side is good, the other bad!" duality.

Jacob's ultimate plan is to change the constants of the Valenzetti Equation
Or rather, he wants to save humanity from itself. Which is why the Dharma initiative also found the island ideal for this purpose. He brings people to the Island in order to see if this time they don't try to kill each other, signaling that something has changed that will allow humanity to survive. This reconciles his apparent kind nature with the kind of callousness that would call people fighting and dying "progress" towards an end. His enemy doesn't believe it can be changed, and thus views what Jacob is doing as evil.

Jacob catching a Red Herring is NOT a Red Herring !!!
The Red Herring is Locke's soul
 * Either Locke's soul in in that fish or... it's that glow in the Source Cave?

Jacob and his enemy are Atem and Seto, respectively
. Notice all the Egyptian mythology references? Clearly the "loophole" revolves around the fact that Seto has to defeat Atem in a game- with no Duel Monsters cards or equivalents to use, Seto is forced to "play games" with the main characters' lives instead.

Jacob is a Djinn who granted Richard Eternal Life
Richard has remained un-aged for countless years. He is refereed to explicitly as the advisor on the island. Advisor is another name for vizier. He has since used all his wishes. Furthermore, at one point Benjamin Linus speaks of a magic box that, anything you can imagine, appears inside of it. John Locke's father appears inside it, almost by magic... The second character from the season 5 finale--refereed to as Esau [a reference to the sons of Isaac from the book of Geneses] on various internet forums--is his former master who became a Djinn in a wish taken literally, who wishes to take revenge on Jacob for the subversion of his wish.

The Others are descended from the surviving crew of the Black Rock.

 * The Others have been living on the Island for longer than any other faction we've seen so far.
 * The flashback at the beginning of "The Incident" shows an 1800s sailing ship--almost definitely the Black Rock--arriving on the island, seemingly brought there by Jacob. From the conversation between Jacob and Esau, we can assume that the arrival of the Black Rock was the first move in this game that the two are playing (or infinitely more likely, playing again).
 * The Others are an important part of the game. Jacob sends his emmisary, Richard, to give the leader of the Others his instructions.
 * And it's a bit of a thin one, but the leadership structure of the Others is similar to the chain of command on a ship.

Benjamin Linus was "corrupted" into a pawn of Esau as a boy.

 * Richard took young Ben to the Temple to be healed as a child, and the experience "changed" him. It's sort of a given that whatever happened in the Temple resulted in Ben becoming the Magnificent Bastard that we all know and love.
 * There were still traces of it before the healing. "Hello, I'm little!Ben; I encourage my pet rabbit to hop through a sonic fence to see whether it's active or not. Later on, I'll steal my dad's keys and crash a burning van into a house as a distraction."
 * If we assume that Smokey the Monster is Esau, then the Temple is Esau's domain, in the same way that the Statue is Jacob's.
 * The theory goes that Richard asked Esau to heal Ben, and Esau agreed to do it because he could use the opportunity to change Ben from an ordinary DHARMA boy into a Magnificent Bastard, the perfect Unwitting Pawn for his scheme to kill Jacob. The Temple is almost certainly part of Jacob's domain, not Esau's.

The Loophole is that only the leader of the Others can see or interact with Jacob.

 * When Ben and Locke returned to the Island, the natural assumption is that Locke was the leader of the Others since he had been declared as such before he left.

Jacob and/or Jacob's nemesis is responsible for all of the unexplained apparitions.

 * Up until the Incident, pretty much everything that happened to the Losties involving them seeing people from their past could be equated to "The Island did it." or "They're hallucinating." However, now that Jacob has officially entered the picture as a material character, it has been made clear that he has played an active role in shaping all of their destinies. Jack has seen his father several times, and his father, or at least the image of his father, has now taken residence of Jacob's cabin, with Claire in tow. You could tally this as a substantial example of either Jacob or his nemesis, taking the form of someone dead. Other examples include Boone speaking with Locke in his sweat lodge(Jacob), and Yemi speaking with Eko before his death(Nemesis). Note the line that Yemi says, "You speak to me as if I were your brother." (paraphrasing) That, combined with the telltale eerie Lost sound, sends a pretty clear message that there was something significant about it.
 * Partially Jossed.

Let's discuss Jacob's Plan for a second.

 * Everyone is going on about how Jacob's enemy staged this huge Ganbit Roulette to get rid of Jacob which makes him the Big Bad of the series. But no one remembers that Jacob said "they" were coming, which made his enemy nervous. I think "they" are going to be the real Big Bad of the series, and Jacob used his enemy and the main cast to stage an even bigger Gambit Roulette so everyone will be able to take on whoever "they" are, including his nemesis. Who are they: space aliens. Of course, given how duplicitous everyone on this show is, Jacob could be pulling off some other trick and still be the massive Island avatar jerk everyone thought he was.
 * It's pretty much implied THEY are the losties that are in the 70's!
 * YMMV. This troper thought it was Ilana's group of people.
 * It's still uncertain, but it seems likely that he's referring to the 70's Losties, since.

The Omega Point will somehow come into play.

 * In "The Incident," Jacob is reading Everything That Rises Must Converge by Flannery O'Connor. Great care is taken to make sure the audience can read the cover. However, the point isn't the book itself, but that the title is a quote from Pierre Teilhard de Chardin, who originated the concept of the Omega Point--the cause and end state of the evolution of consciousness in the universe. Somebody--Jacob, Hanso, DHARMA--is trying to hasten humanity's evolution into/joining with the Omega Point, and the Island is the means.

Jughead comes from 2007.
With present-day technology, it probably is possible to fit a nuclear bomb into a backpack. In 1954, not a chance. Even if it's just the fission core. So Jughead was made in the present, specifically designed so Jack could transport it by himself. Then it was sent back to the 50s, disguised as a period-appropriate bomb. Sayid should have known something was weird about it, so he's in on the scam.
 * Faraday, too.

The "sickness" and all those "quarantine" stamps are a result of nuclear fallout.
This is why everyone in the Swan station needs those injections and the yellow suits.
 * This is also why pregnant women always die. According to the CDC, radiation doesn't cause the effects seen in the show, so maybe the island is manipulating the radiation to prevent the Others from having more offspring.
 * And the hydrogen bomb caused it all. Yes, it's fitting together, I think....

Ben has been manipulated by Esau for a long time.
Esau was the one in the cabin who has been posing as Jacob in order to get Ben to believe in him and do what he wants. Ben and the Others thought that they were following Jacob's orders but they were really following Esau. Christian Shepherd, Yemi, Locke's visions were all manifestations of Esau. Esau's plan was to make Ben think that Jacob was the one responsible for what's happened to him, to get Ben to turn against Jacob. As for why Esau picked Ben to be the one to kill Jacob, Ben already has murder in his heart. He's killed many people, including his own father. He's been "corrupted". He's been Esau's ever since Esau healed him as a child (Richard saying that he would "lose his innocence"). Locke could be led by Esau, but not corrupted, because he isn't a killer. The island/Esau tries to force Locke to kill his father, but Locke can't do it, getting Sawyer to do it instead. Therefor Locke could not be the one to kill Jacob, but Ben could. Or something.

Richard Alpert is really Randall Flagg.
Both unaging, both disarmingly handsome and charismatic. "Richard" is either Flagg's true name or one of his more common aliases. And the "Ultimate" edition of the novel ends with Randall Flagg reincarnating on a beach on a secluded island, planning to corrupt the natives.
 * Unfortunately for this theory, Ricardus ain't evil to anyone except himself, going by his backstory.

The trees do not have epilepsy.
The vast quantity of squirrels living inside them do.
 * And the monkeys we never see.

Ben was not supposed to be on the Island.
It's part of the reason Jacob wouldn't talk to himu and seemed to hate Ben. Also why Esau had Ben kill Jacob. Ben was supposed to die when he was a child, but when the time traveling started up, it saved his life, screwing up Jacob's master plan. That's why Ben is the loophole, the only way to kill Jacob.

"Dogen" is Gendo Ikari
Dogen being a new character played by a Japanese actor who's going to appear when the show returns. Reasons: If you're going to do a Mind Screw series why not go all the way; or, The parade of disappointing dads contiues! I don't watch either show and that's the first thing I thought of when I read that name in Entertainment Weekly; you'd think these guys would be a bit more creative in their anagrams. Does he have a dead wife named  and a son named Jishin who work for the VERN company?
 * Oh jeez... if this means we're headed for a NGE-style ending...
 * One of the recent has shown that he has a son, at least in them; if said son   then he is most definitely Shinji.
 * Except, of course, that Dogen is named for Dogen Zenji, a Japanese Buddhist teacher of the 13th century whose most famous written work was The Treasury of the Eye of the True Dharma.

Jacob and "Esau" are... well, Jacob and Esau.
The reason Esau is trying to get revenge on Jacob is for stealing Isaac's blessing all those years ago.

The island is Rokkenjima.
Everything can be explained on the island with magic and witches.

Along the lines that a massive game is being played; 'The Rules' state "No killing members of your own team."
Daddy Widmore cannot kill Ben or Alex because all three of them are identified as Others. He can, however, *hire* Keamy-- an objective third party-- to bloody his hands on Widmore's behalf. The rules have not changed. But Widmore found a loophole of his own.

The Show was meant to be a massive Noodle Incident
The basic idea is that the writers themselves don't know full what is going on with the Island. They have some ideas in general but they worked out a brilliant system, the Noodle Incident is the whole show. Viewers try to puzzle out what happened, will watch each episode to follow it, and dozens of fans will speculate. They can keep stringing things along, keep as many theories going as possible and they never need to 'advance' the actual central plot because there isn't one. When they finally decide to wind things down the comb through fan theories and ideas and pick the one that works best.

Aaron and Ji Yeon are very, very important.
Aaron was conceived off the island and born on it; Ji Yeon was conceived on the island and born off it. They're also very close in age, and it's implied they'll meet sometime.
 * There's also little Charlie Hume, who wasn't born or conceived on the island, but his father spent awhile on it and he's named after someone who died there.
 * Threesome of Fate?

The Island is R'lyeh
The 6'th season premiere opening shows that.
 * Also revealed in the 6'th season premiere is the fact that
 * Thus, the main underlying plot of Lost centers around Jacob, a guardian assigned to prevent C'thulhu from escaping the island and ending the world.
 * Thus, the main underlying plot of Lost centers around Jacob, a guardian assigned to prevent C'thulhu from escaping the island and ending the world.

Jacob's Shack is The Shunned House.
A man-eating cloud of fog? Sounds about right.
 * Holy crap! I never made that connection! In that story the monster is a sort of Eldritch Abomination version of a vampire. Interesting...

Juliet, like Desmond, is exempt from the rules of time travel

 * By, Juliet is the only person to successfully change the timeline. Everyone else is unable to avoid You Already Changed the Past, but Juliet can change things because she is exempt. This is also how she knows that the plan succeeded while everyone else believes that it failed.
 * This may have been Jossed already as
 * Alternatively, it's the energy buried beneath the Swan station that is exempt from the rules, not any particular person. Desmond gained his powers after being exposed to this energy, and the alternate timeline was created by detonating a bomb right in the middle of it.

The Monster is not evil. In fact, it is exactly what Rousseu and Locke called it in the first season.

 * Which is to say, Ol' Smokey is both the spirit of the Island and its "security system". With this in mind, consider his/its conversation with Jacob in "The Incident". It has a very dim view of humans -- this is probably because it is a nonhuman that lives on an isolated island. Our reputation probably procedes us, and therefore Smokey mistrusts humans by default. That's why it/he keeps judging people. Smokey is not malicious -- it/he may not even have a concept of evil -- it/he is just acting in self-defense.

The Others, at least the kidnapping portion of The Others, are essentially like The Gobblers.

 * Let's see here. A mysterious group with shady intentions; check. Possibly in allegiance with a larger, far shadier organization; check. Operating from a remote location that ninetheless has state-of-the-art facilities; check. Obsessed with children and kidnapping them to run experiments on them; check. Possibly looking for a special ability that only the children posess; check and double-check.
 * For the curious, more Lost/His Dark Materials paralells can be read here. A little old and a little outdated, but still worth mulling over.

The Island really IS Purgatory...
...for The Monster.

The Island is Actually a Giant Turtle, and The Characters Are Its Dreams

 * Everything you see on the island is built on its back, as vegetation has formed over the centuries that this ancient Turtle has slept. The Turtle is an immortal force of nature, having come from before our universe began and will continue after this universe ends. The Earth to it is nothing but a nice resting area. The Turtle's power is so immense and elemental that its dreams affect the time and space of our own reality, thus explaining all the time travel and multiple universes. Jacob and the Man in Black/Smoke Monster are actually just characters in the dream, everybody else is "real" but they have been entangled in the subconscious chaos formed by the Turtle's waking. In the final episode the Turtle will awake, and all will know its might.

Jacob and Esau are both monsters that can be contained by the ash

 * Jacob was trapped in the cabin and asked Locke to help him. Once the circle of ash was broken he was able to travel freely about the island. Before that the smoke monster had free run of (most of) the island and since we know that Smokey is Esau then Jacob was definitely in the cabin. Jacob may be a smoke monster as well or he may be able to take another form (such as a flash of light). They both have the ability to inhabit/duplicate freshly dead bodies as Jacob has seemingly done with . The only question I have then is who has been inhabiting/duplicating Christian?

Jacob is in Sayid's body

 * When Jacob died, he did not fight back, suggesting that he had a plan that Esau was not aware of. It is possible that Jacob holds the ability to possess bodies while having access to the host's memories. Presumably he wants to use the rest of the Losties as a way of defeating his nemesis and restoring his place as the one running the island.
 * Well, we know he's
 * This theory could still be valid, though. In earlier episodes, the Others always seemed to get anxious whenever any mention was made of Jacob and don't forget that his first appearance was pretty scary.

The dark water in the spring represents

 * Due to their reactions at the darkening of the water,

Lost occurs in the same universe as Y- The Last Man.

 * The disaster everyone is trying to prevent is the disease that kills off all of the males.
 * The war that is coming is actually the battle of the sexes.
 * Jossed. Hurley can be seen reading a Spanish-language edition of Y in one episode.

Closing a corpses eyes allows them to be 'claimed'

 * This is why Ben closed Horace's eyes out of respect but no one else's. He wanted Horace to be possessed (possibly an order given him by Jacob)
 * Also- burning a body prevents any chance of 'claiming'

The series will end with Jack taking Jacob's place and all the other characters, including Richard and the Others, leaving the Island.

 * The conversation between Jacob and the Man In Black at the start of "The Incident" indicates that the events occuring in the series are merely the latest iteration of a cycle of events. Both characters talked about the cycle ending at somepoint.
 * In particular, when Un-Locke suggests "it never ends", Jacob's response is "It only ends once."
 * The Man In Black wants to "go home", which presumably means leaving the Island. If that's his ultimate goal, then presumably it's also the point of contention between him and Jacob. In effect, the Island is a prison, the Man In Black is a prisoner and Jacob is his warden. Following the analogy, the Others (and it's been all but comfirmed that they originally arrived on the Island as slaves being transported on the Black Rock) are Jacob's "deputies".
 * Jacob is dead. If the Man In Black is going to remain imprisoned on the Island, someone needs to replace Jacob.
 * The above two were partially confirmed in 6x09. Though Jacob uses the analogy of a cork in a wine bottle, he effectively admits that the Island is a prison for the Man in Black (a force of evil who cannot be allowed out into the world), who will remain imprisoned as long as the island has a guardian, either Jacob or someone else.
 * So, my conclusion on what's going on and how the series will end:
 * The "cycle" that Jacob and the Man In Black refer to is the latter's attempts to escape the Island by manipulating people into setting him free and/or killing his jailer. Jacob has to combat this by convincing people to help him, or at least by using the Others to stop those who would free the Man in Black.
 * The current cycle is almost complete. The Man In Black has manipulated the Losties and Ben into killing Jacob and he's probably almost finished whatever he's doing to get off the Island.
 * Somehow, the Losties will figure out a way to trap the Man In Black again and stop him from trying to escape for a while. Someone will need to stay on the Island and guard him, taking up Jacob's old task, and Jack will wind up with the job. He'll gain whatever immortality or powers Jacob once had.
 * To stop any immediate threat, everyone except Jack will leave the Island. That includes Richard, all the Others, all the Losties, the Ajira 316 survivors--everyone. That'll just leave Jack and the Man In Black, alone on the Island for years.
 * The final scene(s) of the series will be the beginning of the next cycle: whether it be a shipwreck or a plane crash, more people will arrive on the Island by accident. Jack will try to deputise them, creating a new group of Others, while the Man In Black will try to manipulate them into setting him free and/or killing Jack.
 * I imagine that one of the last scenes of the finale will be almost identical to the opening of "The Incident", with Jack instead of Jacob.

The Numbers correspond to Bible verses.

 * Jack's name on the cave wall is listed as 23. The first line of the 23rd Psalm is "The Lord is my SHEPHERD".
 * The other name/number correlations may refer to The Psalms, or some other Biblical or non Biblical connection to that person.

One or both timelines have become an Epiphanic Prison
If it's the timeline where they're still on the island, they'll only get out when they understand everything that was going on. If it's the one where they aren't on the island, they'll get out by understanding what's gone wrong in their lives and why. If it's both timelines, they'll escape both and find a third reality.

Jacob and Esau are one and the same.
Because why the hell not?

The Island sinking works similar to how the island floats in Cave Story.
Contains unmarked spoilers for Cave Story and Seasons 5/6, but anyway: In Cave Story, the Island is kept afloat by the Core and pulled down by Ballos. After the player destroys the undead Core, he (assuming you've done all the prior requirements) has the option of either escaping from the Island, which causes it to fall and crash into the earth, or descending into the "Hell" level, where he (assuming you don't just give up at this point) kills Ballos, preventing the island's fall. The bomb and the Swan energy pocket may work something like this. Perhaps the Island would have sunk as a result of the energy discharge (what with all the magnetic collapsing equipment and etc.), which happened independently of the survivors' actions, had the bomb not gone off, cancelling out the energy, but still causing enough of an incident to be "The Incident" referred to in the episode title and orientation video. In other words, the bomb not only caused the Incident, it prevented the sunk-island timeline from originally occurring. The sunk-island timeline is indeed a spin-off timeline made by the decision, but unnecessary for the existence of the original timeline, unless Juliet time-travels between them, as a result of the Swan energy time travel exemption theory listed above, in order to detonate the bomb when she does.

The Smoke Monster is a nanorobot swarm like in Michael Chricton's Prey.

 * That doesn't explain why he is "stuck in that form", but...
 * This was specifically Jossed several years ago by the producers.
 * Where? I would like to read.
 * Smoke+ %22Monster%22 Here.

The Smoke Monster doesn't cross ashes streams because of fear.

 * Someone, somewhere, prophesized he would die the day he crossed one. Much like Arthur Dent was prophesized to die was told he would kill someone in a place called Stavromula Beta, and spent the rest of his life avoiding to go to there, which he assumed it was a planet.

The alternate timeline isn't the result of the bomb going off.

 * The bomb didn't work, and the flash was merely them traveling into the future, as they conclude in the island timeline. The off-island timeline was not caused by the bomb going off, but is a timeline where the island was sunk by something else that happened in the past. Several things in this timeline are different that would not have changed if the sinking were the result of the bomb, leading to the conclusion that there was some other major difference that led to the divergence of the timeline. Jack has a son, Locke is still with Helen, but most importantly, Ben is alive and teaching history. If the island had sunk when the bomb went off, he would have died as a child in 1977. It's implied that he never went to the island in the alternate timeline, and perhaps the reason for this is because the island sunk some time in the past, and in this timeline, there was no dharma initiative, no island, and thus Ben doesn't end up stuck there with his abusive father, and grows up to be a normal, well-adjusted human being.
 * Ah, but think about this: Ben's getting shot is a direct result of Sayid and the other Losties crashing on the island in 2004 and later travelling back in time. So if the bomb goes off, then Oceanic Flight 815 never crashes -- and this in turn changes the past to eradicate the time-travellers' influence from the new timeline altogether. So this results in Jack having a son, Locke still being with Helen, etc., and Ben not having been shot in the first place. (Apparently the time-travelling Losties' influence also kept the island from sinking at some point -- perhaps in the '50s without Daniel's advice to bury Jughead, or perhaps even in this timeline's version of "the incident" in which nobody set off the bomb.)
 * I wasn't referring to Ben getting shot, I meant he would have died if the island sunk in 1977, since he was on it at the time. But obviously things are different in the alternate timeline, so perhaps in that timeline he was never on the island?
 * This, to me, is confirmed by the episode "Dr. Linus". If the bomb directly caused the island to sink in one timeline, Ben is dead in that timeline. But we know he is actually alive in that timeline and what's more, he appears to be a good man since he didn't sacrifice Alex for a promotion. This is evidence that he was never corrupted by the island, meaning that Sayid never shot him and the temple never healed him. So to me there are two options: 1) The bomb didn't sink the island. Later in S6 we will find out what did. 2) Blowing up the bomb in 1977 effectively destroyed the island way before 1977 (sometime before Ben and Roger got to the island in the original timeline... probably as far back as, say, the creation of the island?). So the alternate timeline reflects this - Ben and Roger never went to the island and Jacob never touched (changed the lives of) any of the Losties.
 * Except that Roger clearly says that him and Ben were members of the Dharma Initiative and that, at one point, they had to leave the island.

Charles Widmore will die of a fatal heart attack.
Most likely after Penny has disowned him (if she hasn't already) and helped along by a gold-digging much younger wife.

Red Sox lost the World Series.
For some reason the island not existing causes the 2004 Red Sox to lose the World Series. Thus reassuring Jack's reccuring pessimistic statement.
 * To take this WMG further, this was the entire purpose of the show. Jacob is a die-hard Yankees fan, and he was willing to launch an elaborate plan and kill a few people to keep the Red Sox down. Need more evidence? We now know the Numbers were selected by Jacob because he liked them. Why? Because all of the numbers are ones whose jerseys the Yankees have retired, with the final, key number, 42, being retired by every team in major league baseball (it's Jackie Robinson's number). The Monster opposes him, and so he took the form of Christian Shephard, a loyal Red Sox fan like itself (obviously, the Monster is the Green Monster, too).

Jacob is from the same species of sentient supernatural beings as the Other Mother

 * That's why he leads a team called "The Others"
 * The island is placed in a pocket universe semi-isolated from real world, like the Other Mother's world.
 * Just as Coraline once walked that world and come back to the place she started, Desmond sailed a lot only to come back to the island.
 * The world/dimension which the island is placed has some contact points to the real world, like the direction they told Michael to navigate to leave the island with Walt, and like the hole Coraline follow the rats/mice.
 * Just like Coraline parents, Desmond realizes "We're stuck in a bloody snow globe!"
 * Coraline was the Other Mother's candidate.

The flashsideways are Juliet's Dying Dream

 * So she said "it worked".
 * So in there, she hadn't had to do Jack's appendicitis.

Jacob is also a smoke creature

 * Many apparitions of "smokey" can be his.
 * He could've killed Mr Eko, for example, instead of Esau/Unlocke.
 * Alternatively, Jacob is similar to Smokey, but his normal form is bright white light. This is how Locke described what he saw after the first ever (offscreen) encounter with the apparent monster, and would fit in well with the darkness and light theme that the show has.
 * That could be related to a biblical theme: the pillars of cloud and fire that guided the people through the desert, in Exodus.

Desmond is an asshole who put together the events that killed Charlie so Desmond would be able to get off the Island and be with Penny.

 * Considering what actually happened, I dunno if this qualifies as WMG so much as "obviously true". To date, Claire, who Charlie killed himself for, is stuck on the Island, and is now crazy. Charlie is quite dead, and Desmond seems to have had a happy ending. Hell, even in the alternate reality, Charlie is still screwed.
 * How is that Desmond's fault?

The Island makes people insane.

 * Really, it's the only explanation for much, if not most, of their behavior. Rose is immune for a similar reason that Richard is immune to Kahlan's power; she's truly happy. Granted, I'm only up to season 3, but I've not found anything to countervail this Guess yet.

Lost is a Scion-Story
And Jakob and "Esau" are Scions of Sobek, banned on the dangerous Island by their father for a harsh crime, unable to kill each other. To harm the other one, they need mortals with good legend points. The whole story is in the perspective of the mortals that get more and more fate bound by these Halfgods.

The entire show is now a spin on Charlie and The Chocolate Factory
MiB is the guy with glasses who asked the kids to sneak out the recipe for him.
 * Strangely enough, I'll vouch for this. The latest preview had an overlapping of the Tunnel Scene (audio) in the background.

The flashbacks in Seasons 1 through 3 were actually the Smoke Monster reading the Islanders's memories.
In Season 5, it was confirmed that the Smoke Monster can store and replay people's memories when it did so to Ben in order to convince him to not kill "Locke" (who was actually the Smoke Monster). It's quite likely that it did this to everyone on the island in order to find some personal issue that it can manipulate for each person so that he can use them in his plans. After all, if he can build up a good profile on each Islander, it'd be that much easier to keep them in control and manipulate them. Note also that many of the flashbacks occurred while the characters were in the jungle, which is the Smoke Monster's home turf.

Claire died and was resurrected.
Dogen clearly says that Sayid's in danger of ending up like Claire, and they both become homicidal allies of the Smoke Monster. But Sayid died and was resurrected before he started acting weird, so obviously Claire did too.

Jacob and Esau represent the Seelie and Unseelie Faerie courts, respectively.

 * Cause, let's face it, neither of them is exactly 'good', and they sure as heck aren't honest. They act like The Fair Folk.

What we see in the flash-sideways is the original, unaltered timeline, and the Island timeline is the result of temporal meddling.
The off-Island flash-sideways timeline, with Detective Sawyer, Dr. Linus and Jack the daddy, is the original timeline of the Lost Universe. Someone or something happened to change the timeline and cause these people to live different--arguably worse--lives, ultimately end up on the unsunk Island and become the pawns of Jacob and the Man in Black.
 * Arguably, Jossed. In the AU it's implied from Charlie's and Desmond's near-death experiences, and extended by the Daniel Faraday of the alternate timeline, that the AU is "wrong", that it wasn't supposed to end up that way. Desmond's work is an attempt to put the timeline back in its correct path.
 * Definitely Jossed.

Esau and Jacob are past/future hosts of Ruin and Preservation.
They have the same "black and white" theme going on, and on at least one occasion Ruin appeared as a mass of black smoke. The "anomalies" at the Swan and the Orchid are presumably their Wells.
 * Ok, scratch that last bit, the finale made it very clear where the Well of Ascension is.

The Man in Black is Becoming the Mask.
When confronting the mysterious boy in the jungle, he shouts Locke's Catch Phrase: "Don't tell me what I can't do!" And in "Recon," he tells Kate that he had a crazy mother--an attribute shared by Locke, whose own mother claimed he was the result of a virgin birth. Is it one of the show's usual non-coincidences, or is it ol' MIB mistaking one of Locke's memories for his own? Furthermore, in "Dr. Linus," Ilana says that MIB can't take any other form now--he's stuck as he is. Because he's becoming too much like the real Locke to impersonate anyone else? And when he asks Desmond "do you know who I am?" Desmond answers "Of course--you're John Locke." Maybe Desmond doesn't know who MIB is, but maybe he knows that which Smokey doesn't want to acknowledge: that's he's becoming Locke in more ways than mere outward appearance.
 * There's even more support for this in recent episodes: when Desmond tells Locke he's not afraid, Un-Locke's facial expressions seem to vacillate back and forth between his own and the more cheery expressions of John Locke. To this troper that suggests that John Locke's personality is trying to reassert control. The issue of fear is also significant since the one thing that distinguishes Locke from Un-Locke in the eyes of Sawyer is the fact that John Locke always looked a little afraid, while Un-Locke seems to have no fear at all. Indeed it's Desmond's lack of fear that seems to cause Un-Locke the most consternation.
 * This was all but confirmed by "Across the Sea". Jacob sends the Man In Black's body down the glowing tunnel and the Smoke Monster comes out. The Man In Black clearly did not transform into the monster as his body is found later. Hmm...

Jacob and The man in black are Philemon and Nyarlathotep from Persona.
Jacob and Philemon try to prove people are good; MiB and Nyarly tru to destroy people by manipulating them. Jacob and Philemon choose to act through proxies granted special powers; MiB and Nyarly act more directly.

Eloise Hawking is (at least partially, or possibly fully) responsible for the creation of the flash-sideways timeline.

 * The "whatever happened, happened" rule of time travel ultimately condemns Eloise's son, Daniel Faraday, to die at her hand in 1977. The only way she can save him from that fate is by creating an alternate universe in which there is no Island and Daniel isn't a physicist.

The flash-sideways universe is the same place that Sam Tyler and Alex Drake were sent to.

 * Sam gets hit by a car, wakes up in some version of 1973 that's populated by (past incarnations of) people he knows, and he eventually realises is the perfect place for him.
 * Alex gets shot, wakes up in some version of 1981 that's populated by (past incarnations of) people she knows... and I haven't seen enough of the series to know how the rest goes.
 * The Losties are at ground zero when a hydrogen bomb collides with an enormous pocket of unstable electromagnetic energy, they wake up in some version of 2004 that's populated by people they know, and this place is kinda perfect for them (and kinda not at the same time).
 * So basically, the only person who can stop the Man in Black and save the world is DCI Gene Hunt and his team of armed bastards.

It's going to end with an epic Battle Royale With Cheese.
Everyone will get their memories from both the original timeline and the flash-sideways combined, then the FS versions of all the dead characters will show up in the OT for the final battle with the Man in Black. This way Boone, Shannon, Ana Lucia, Libby, Eko, Charlie, Michael, Charlotte, Daniel, Juliet, and Locke can help save both worlds. Best scenario: Jack and Locke deliver the finishing attack together.

The Alternate Universe is screwed.
"This world doesn't matter." --AU Charlie The AU is an imaginary universe, a theoretical impossibility that exists anyway: the root-of-negative-one-verse if you will. Why? Jacob, that amoral Magnificent Bastard time master made it so it could function as the new bottle. When the final showdown comes, Desmond, bolstered by his understanding of the conflict and his own unique role in it, will offer himself as a bridge to the AU once the Lockeness Monster's original plan fails (as it must). Desperate to flee his prison, LM jumps willingly into the AU. Eventually, (say around the time that regular-universe season six comes to a close), things start reverting to their natural state and, without the Island or its mythos, it locks him away in an eternity of pure nothingness.
 * I think this is probably the best theory I have heard and could very well be true.

The Monster originally was imprisoned somewhere under the island's surface.
So.. there are wells. More than one according to Monster and they were made to find the power source of the island. And instead of power people who created wells accidentally found and released the Monster. Ooops!
 * An extra that came with the super-shiny DVD release of season 5 was a written copy of the Truce between the DHARMA Initiative and the Others, signed by Richard Alpert. A clause that Richard inserted was very specific about the DI being forbidden from drilling a certain distance (I think about 10 feet below sea level) into the soil of the Island. Which is suggestive, and ties into your theory.
 * Jossed. The Smoke Monster was free and active when Richard first came onto the Island, ergo it was already tooling around prior to the truce with the DI. Makes no sense for Richard to demand a "no drilling" clause when the Monster's already loose on the island. On the other hand, the truce might have specified a "no drill" clause so the DI didn't penetrate the electromagnetic anomaly and set off an incident ... oh, wait.
 * And now, as of "Across the Sea", it turns out that the Man in Black himself dug at least one well, so he might have been responsible for the other ones, too.

One of the last episodes will be all about the dead Main Characters.
Considering the focus on them in the Flash-Sideways, Ilana's abrupt death and Micheal's reveal that the Whispers are the dead trying to communicate with the living, it's not too farfetched- and could possibly form a bridge to the FST, considering how near-death experiences trigger memories.
 * Sure as hell looks to be Jossed as of the penultimate episode...
 * Turns out the  was all about the dead main characters.

The Island is a prequel to the events of the The Dark Tower.
Temples, artifacts, and locations built by a vanished creator civilisation? Check. Instabilities in time and space, presaged by a high, keening noise like a thinny? Check. Without a number of particular individuals forming a ka-tet, everything will fall apart? Check. Thankee-sai.
 * More seriously, the makers of Lost have gone on record to say how much they like Stephen King's book series. Canonically, Un Locke is the Man in Black. That's not a coincidence, for it would appear that the Man in Black is none other than Randall Flagg. (Or there's a possibility that ol' Smokie is the Crimson King.) Jacob is a Gunslinger -- or even Arthur Eld -- whose only task is to keep Randall Flagg locked up so he can't escape and start working to free the Crimson King. The Island works as a prison for the Man in Black -- because it's a node on a Beam to the Tower. Unfortunately, because Jacob is now dead and the show will probably end on a Downer Ending, the Man in Black/Randall Flagg is then free to commence roaming End-World and setting plans in motion to free the Crimson King ... which is where Roland of Gilead comes into it.
 * Further to this: Since they got to the Island, everyone from Jack down has suddenly become really, really good with firearms. They're all Gunslingers!

The polar bear is really a panda.
The polar bear was actually a panda that was born all white and was owned by one of the Others but it escaped and lives in the forest trying to avoid humans. Which explains why there was bamboo on the island and why the losties never see it again.
 * Nope, it's just one of the candidates. Jacob touched it in a Chinese zoo.

The Island will be rendered completely powerless and ordinary by the end of the series.
There's gonna be some kind of big conflict in the finale, possibly resulting in the death of the Man in Black. But whatever happens, that core "thing" that makes the Island so magical and fantastic--this power that heals people, allows it to travel through time, keeps it hidden from the rest of the world--will be destroyed, or used up, or something. The end result is a case of The Magic Goes Away, and the Island just becomes an ordinary island in the middle of the ocean, completely unremarkable.
 * This troper thinks that would be the most tearjerking ending possible for the series.
 * However, it would certainly ensure that the "cycle" ends. If the Island stays around, then what happened to the Losties will certainly happen to someone else.
 * If this happens, the suggestion seems to be that it's quite literally a case of Rocks Fall, Everyone Dies, given that the core thing that makes the Island so magical is pretty much tied to the souls of everyone on the planet.

Ben summoning the Smoke Monster in Season 4 has something to do with why he could kill Jacob.
First of all, there has to be some reason why the Smoke Monster would even respond to Ben's call when he did whatever he did so that the Monster would attack Keamy's men. Perhaps whatever he did tapped some power that made him able to do something to the thing. In addition, the reason why the Monster (as Alex) told Ben not to kill "Locke" was because Ben literally had the power now to kill either one of them. There are two flaws to this theory, of course. The first is that the Monster may have wanted to keep Ben from attacking "Locke" so he wouldn't be exposed. Secondly, perhaps Ben could kill both because he wasn't supposed to be able to return to the island. There is still no explanation why Ben was the loop-hole Man in Black needed.
 * This troper seems to remember that summoning the Monster was some sort of emergency mechanism that the Others knew about as an institution to be invoked in the scenario that they were about to be overrun or killed. Makes sense, too; the Monster's trapped on the Island, and pissed off as all hell, which makes it the perfect "death blossom" weapon if you have no other alternatives. As it is, it's implied that what made Ben a loophole was the fact he, not Locke, moved the Island -- only the leader of the Others was allowed to do that, and he wasn't the leader of the Others at the time. The effect threw him off the island, which was supposed to banish him forever -- but he murdered Locke and sort of took Locke's place as the leader of the Others. He could meet with Jacob, because only the leader can; but he was also an exile and exiles normally can't come back to the Island. He circumvented those boundaries, meaning he's not bound to the island's rules. Ben is Neo, just with a better accent (and better acting ability, too).
 * This troper thinks, in hindsight of the fact that the Smoke Monster is a sentient being, that it just wanted to keep Ben a) alive, and b) thinking that the Smoke Monster would help him out when necessary. By playing the role of attack dog, the Monster ensured that Ben would keep playing his part in the master plan.
 * That Smokey was manipulating Ben was given a nod in the penultimate episode.

Jacob is a .
The whole thing is in spoilers, because I'm lazy like that.

Miles is/will be able to read minds
The only reason why his ability has been limited to fresh corpses is because it's easier than reading the minds of living people. Spending time on the island and/or using his abilities more will allow him to eventually extend his ability to living people. Another possibility is that his ability extends to the MIB, who can only take the form of dead people under specific circumstances.

Juliet will become Jacob
This may seem far-fetched at first because she's dead, but remember that the Man in Black became a dead character, so perhaps Jacob can do the same thing. The reasons I see Juliet as the most likely candidate are thus:
 * She predicted the rain in the same manner Locke did.
 * She and Jacob sacrificed themselves in the same episode.
 * Jacob lives under a giant statue of the goddess of fertility. Juliet is a fertility doctor.
 * Jacob is essentially a loner, as is Juliet.
 * She faced down the Man in Black as if completely unafraid.

As of Widmore's EM experiment, Jacob is back and has possessed Desmond. Desmond has shifted to the alternate-universe.
Again, a bit farfetched (but I guess that's why we're on this page) but consider:
 * The changes in personality of Desmond since he was hit with another EM experiment. He's as cool and calm as Jacob, and seems to have that same "fate will have its out" shtick that Jacob did.
 * Additionally, Jacob's turned into something of a manipulator - consider how he (apparently) avoids getting killed by Sayid.
 * Above all things, he's completely unafraid of Un-Locke. Indeed it's that aspect of his character that puzzles and/or troubles ol' Smokie the most.
 * The only creature that never had any fear of the MiB was Jacob.
 * Desmond has also survived a fall from a great height into the well, suggesting Island-favoured health. Possibly his own immortality as granted by the Island is a reason for his lack of fear.
 * We haven't seen any apparitions of Jacob since Widmore's EM experiment.

The Island is a dumping ground for the dangerously psychotic.
If there's counter-evidence to the fact that everyone on this rock is certifiably batshit Ax Crazy, I haven't seen it yet. Sun and Rose (and Bernard, I guess) were mistakes.

The Island draws crazy people to itself.
For entertainment. Goes with "Island as Magnificent Bastard Genius Loci" above. It gets its jollies from running these shithouse rats around and watching the fireworks.

Oceanic 815 was shot down.
Chuck said so!

The Island will
All right, so we know both that They can't leave something like the latter fact hanging without resolution. With only a few episodes left, I doubt that both will get seperate explanations, so I'm going to throw it out there that

The Smoke Monster will be killed by an army of bats
The Smoke Monster is weak against Sonic things so an army of bats using supersonic should kill or at least make him hit himself in confusion. Alternatively Sonic the Hedgehog will kill the Smoke Monster.

It's all one big vicious cycle.
In the flash sideways, Desmond will gather everyone who was important on the island in the OT. Survivors like Jack and Rose, Others like Ethan and Juliet, random people like himself and Rousseau, maybe even new people like David, and they'll all get on a plane (Maybe the FST equivalent of Ajira Flight 316). This plane will suddenly hit turbulence, then BOOM! Title card. THE END. It'd be a pretty fitting conclusion to Flash Sideways considering what we know about course correction.

Juliet and Kate are half-sisters.
As per this theory: http://lostpedia.wikia.com/wiki/Mr._Carlson/Theories Juliet and Rachael may be Kate's half-sisters. We know Juliet's parents got divorced when she was young, and we know she's older than Kate. Now the name is an issue, but what if Juliet's mother's name is Carlson and she changed it along with her daughters' names after her husband left. Said husband's name? Wayne Jansen of course. Wayne has been having an affair with Diane Austen, which results in the birth of Kate. This creates an interesting mirror with the love quadrangle. Sam Austen is Jack, Mrs. Carlson is Juliet, Diane Austen is Kate, and Wayne Jansen is Sawyer. It fits with the character connections theme too and if Jack and Claire can be half-siblings, why not Juliet and Kate?

The Man in Black is really dead.

 * The latest episode has Jacob kill his brother, showing that they can indeed kill each other and that their mother was lying about many more things than she let on. When Jacob kicked his body into the light at the end of the tunnel, the Smoke Monster was able to escape since he then had a body. It absorbed the Man in Black's memories and took his form, but they are completely separate beings. He is not anyone or anything; just a collective consciousness of whoever he has imitated.
 * I think the implication is that MIB's mind, his consciousness, was made manifest as the Smoke Monster, which meant his body was kinda leftover. Which leads into...

Jacob and MIB's Mother (i.e. Allison Janney's character) was also a Smoke Monster.

 * The way she insists with such strength and conviction that Jacob and MiB should never go down into the Cave of Light has this implication that she knows from personal experience that it's a bad idea. And lo, when MiB gets tossed into the Cave, he gets transformed into a Smoke Monster. (see the above theory on reconciling MiB becoming a Smoke Monster with the fact his dead body was buried in the cave)
 * Voldemum appears to be a middle-aged woman, yet she's able to destroy a human settlement and kill everyone there. Doesn't that seem a bit much? Wouldn't people have fought back? Yes... unless she was a Smoke Monster, in which case it's all easy as pie.
 * But I hear you all asking, "Bronzethumb, you sexy devil, how was the Man in Black able to kill Voldemum if she was a Smoke Monster?" The Man in Black stabbed her with the same dagger that would later be given to Richard and then to Sayid. And what's more, he stabbed Voldemum before she could say a word to him.
 * On the other hand, the Island seems to grant enormous physical strength and stamina to those who are protecting it. And it's arguable that the massacre of Un-Locke's people didn't take place until after she'd shown Jacob the Source and made him one with her. One middle-aged woman taking down a bunch of people on her own is a bit incomprehensible, but if it's her and Jacob together ... what? It worked for Lucius Vorenus and Titus fuckin' Pullo! :D
 * Also, there's one big hole in the argument: Voldemum isn't Jacob and Un-Locke's mother. And their genetic mother ain't invulnerable to everything except the Ajanti dagger, her kryptonite seems to be large rocks.
 * When we say "Jacob and the Man in Black's mother", we are referring to the woman who raised them, played by Allison Janney, and not the woman named Claudia who actually gave birth to them.

The Man in Black plans to use the frozen donkey wheel to escape the Island.

 * After all, he was the guy who started building the wheel in the first place. And we know it works, so the question is, why hasn't he used it already? Perhaps THAT is why he needs the Candidates dead, because while they're alive, it won't work for him... somehow.
 * Confirmed as of Across the Sea.

Jacob's not done yet, he's the kid. And he's going to touch a certain buried corpse again...

 * Leading to a Mirror Match between for control of the island.

Jacob didn't create the smoke monster.
Instead, he broke the island. The heart of the island contained the smoke monster, which was originally a nonsentient entity that actually acted benevolently on behalf of humanity. By throwing MiB into it, he gave the smoke monster sentience, killing MiB and imbuing the smoke monster with his mind. This is responsible for every single bloody thing that has happened on the island since. Nice Job Breaking It, Hero, indeed.

Neither Jin or Sun is the candidate "Kwon".
Among the list of names, one of them read "Kwon", which everyone assumed to have meant either Jin or Sun. However, there was one more Kwon on the island. Their daughter, who was conceived on the island, is the candidate.

The 1977 Losties time-travelled to the exact instant that Jacob died.
A certain amount of time elapsed from the moment Ben moved the island in 2004 to the moment Jacob died in 2007. For simplicity’s sake, we’ll assume that time was exactly 3 years. Sawyer and Co. time travelled from 1977 to 2007 on the night Jacob died. It’s not farfetched to assume they came back to 2007 the very instant that Jacob died. There are two possibilities for how/why this occurred. It could also be that the only reason the 1977 Losties came back on the night Jacob died is because the writers/producers wanted both the 1977 and 2007 story arc to climax at the same time in the season 5 finale. They might have figured that events would naturally lead to both Jacob dying and the incident occurring at the “same time” (according to the Losties internal clocks…)
 * First, Sawyer and Co. mentally experienced exactly 3 years of time since the island was moved to the night that Jacob died. When the bomb went off, they went to their “real timeline” in 2007.
 * When Locke turned the wheel and stopped the island from skipping, Sawyer and Co. time-jumped to exactly 3 years before the 1977 incident. EXACTLY 3 years, to the second. For that to occur, whatever/whoever was controlling the time travelling knew exactly when Jacob would die (exactly 3 years after the island moved) and exactly when the incident occurred.
 * Perhaps Jacob was causing the time travel, but he was actively causing it in “real time” according to the 1977 Losties’ internal clocks. When he died he was unable to keep them in 1977 and so they came back to when he died. That’s also why he said “They’re coming”. So it’s coincidence that the Losties were detonating a nuclear bomb at that point. This could mean that the bomb didn’t even go off.
 * Second, Sawyer and Co. didn’t necessarily time-travel to their “real time”, they time-travelled to the moment of Jacob’s death. They did not necessarily experience exactly 3 years of time from the moment Ben turned the wheel to the moment of the incident.
 * Right before he died, Jacob caused the 1977 Losties to end up in 2007. Hence, “They’re coming”.
 * Jack, Kate, Hurley, Sayid, and (most importantly) Daniel came in 1977 a few days before the incident, while Sun, Ben, Lapidus, etc. came in 2007 a few days before Jacob’s death. Both groups of people directly led to the incident and Jacob’s death, so it’s not that big of a stretch to say it’s a coincidence that they occurred at the “same time” according to the Losties’ internal clocks.

The Source is the Chamber of Guf.
An extensive web of connections links the show to Kabbalism (as well as Gnosticism.) The Source is the Earthly manifestation of the source of all human souls. If the light should go out, the light (soul) in each human being, as stated by "Mother," will also go out, as all souls are linked by their origin as fragments of the soul of Adam Kadmon. It's difficult to say what the precise effects of this would be, given that Our Souls Are Different, but it'd definitely be a Very Bad Thing.

The light inside the tunnel?
Marcellus Wallace's soul.
 * After verification, when Jack and Hurley were at the lighthouse, if you were looking carefully you could see that the name associated with the number 108 was Wallace. I love Wild Mass Guesses.
 * Alternatively, it's Locke's soul.
 * Which would make Locke a Time Lord.

There is an older Smoke Monster
Evidence: In the ruins under the Temple, Ben sees a hieroglyph of people cowering before the Smoke Monster. Egypt precedes Rome historically: The Man in Black is the son of a Roman. He was born (and thus transformed) well after the Egyptian structures were constructed. So there must be another smoke monster who is depicted in the hieroglyph. This is the Smoke Monster helped Mother destroy the Roman camp. This is how Mother knows entering the cave is a fate worse than death. Against: there's no explicit evidence that MIB's people are Romans - that only rises from the implication that Teh Dagger is a Roman gladius or something similar. MIB's people are never identified by name. If anything the implication is that MIB's people are some sort of superintelligent "Atlantean" folks, given unlike virtually anyone else before or since they actually seem to have worked out how the Island functions sufficiently to create teleportation effects. Second, while the Egypt of the "classic" period might have preceded Rome, hieroglyphic language does not necessarily do so. Third, "Across the Sea" doesn't show us any statues or Egyptian structures, therefore we can't be certain they were around prior to that episode.
 * We don't know that the structures under the temple were made during the time of Classical Egypt; they could have been made by Others three hundred years ago, or by time-traveling Egyptians two hundred years ago, eighty years ago, and six hundred years ago In That Order. On the other hand, Jacob, "Esau", Voldemum, and Claudia all knew Latin, which (along with Mother's and Claudia's clothing styles) reinforces the idea that they are (at least in some way) from the Roman Empire.

The show exists in the same universe as Monk
May 23rd's series finale will have Adrian show up and explain the mystery behind everything with his classic "Here's what happened..." flashback technique.

Jack is Shinji Ikari.
The end scene in the church is too similar to the "Congratulations" sequence for it to be a coincidence.

There will be a seventh season of Lost
This time, the cast will include grown-up versions of the Losties' children: Ji Yeon Kwon (Sun and Jin's daughter), Charlie Humes (Desmond and Penny's son), Aaron Littleton (Claire's son), Walt Lloyd (original Lostie and Michael's son), Clementine (Sawyer's daughter?), etc...
 * And they will all be zombies.
 * "Lo-stie Babies! They make dreams come tru-ue!" I would watch that show and so would you.
 * I thought it would be about what Hurley and Ben do now that they're running the island.

Conan O'Brien, The Emmys and the characters from The Office and House are all linked to the island.
During the Emmys, host Conan O'Brien traveled to the set of Lost and the Office and House. In fact, he traveled to the actual places and they are linked. These characters are all working off their sins in a purgatory that takes the shape of their various shows.
 * House is doomed to eternal torment in the form of bodily pain and having to constantly deal with his intellectual inferiors. But the torment is a byproduct of his attitude and once he realizes it, his personal hell will become a personal paradise.
 * Jim, Pam, and Ryan's characters are all still being tested. Ryan failed his test, having become a Corrupt Corporate Executive and then fallen from grace. Jim was tempted by the dark side but then gave up his management job and went back to sales. Pam's test is yet to come.
 * Conan suffered his test at the hands of NBC management and Jay Leno. Having passed, he ascended to a better network.
 * And they will all find each other again some day at an Emmy ceremony. It will turn out it was all a construct of their minds to help them find each other again because that fateful night at the Emmys was the most important time in all of their lives.
 * They will be miffed when they find out that the Losties formed their own clique and ascended first.

The writers of the show are in Purgatory
In life, they were the writers for Gilligans Island. Now that the show is over, they can all ascend.

The Ending will not actually clear anything up.
Proven true?
 * ...Maybe?

The Final Fate of the Ajira Six.

 * Kate will end up in prison for violating the terms of her parole.
 * Miles will live like a king with the diamonds he dug up from Nikki and Paolo's grave.
 * Richard will resume his career as CEO of Mittelos Bioscience.
 * Sawyer will become a good father to his daughter. (By contrast, Claire will have a strained relationship with Aaron.)
 * Lapidus will be fired because nobody at the FAA will buy his crazy story about what happened to his passengers and crew.

The Island is a Primordial that ran away during the Primordial War.
Jacob and the Man in Black are the most prominent of its third-circle souls. Though it seems unlikely that either of them was the fetich, since would have changed the island pretty drastically.
 * Richard was given some kind of bootleg Exaltation by Jacob to stop his aging, making him a kind of pseudo-Infernal.
 * Ben is a Sidereal. was all part of a plan leading up to... something.

Desmond .
Firstly, he can't be killed by the island's electromagnetic, ahem,... oddities, because of whatever it is that makes him unique. Second, after becoming unstuck and finding his Constant, Penny, he has effectively become at least something similar to a living Story-Breaker Power, it seems. Third, and this is the biggie, Or something. In short, I guess I'm saying if you ask me,
 * But then how could he
 * Though it's not like we can apply real world logic to what you can do . So maybe is possible.

Jack will .
Well, there's the fact that he got dumped into the light and came out, found in a random area almost exactly like Nameless was. Now, I may hear you say 'but wait, he was alive', well think on it. Look at how deep the waterfall is, and look at how Nameless went over it. Chances are he died in there, or similar, Jack did not due to his stab wounds. Hurley is the new Jacob, perhaps there needs to be a Nemesis - they necessitate one another. After all, Nameless was decent, if troubled, before, and then he became an absolute monster - literally. (The reason he is it rather than just another body for it is the previous one's mortality, and subsequent ejection-over-a-cliff.) It seems a logical (as far as Lost is logical) explanation for why Jack survived where only Desmond should be able to.

The Island is a part of the Kingdom Hearts Multiverse.
The light at the heart of the island that's inside of everyone and everything? The door at the end? The smoke monster? It all makes too much sense.

What about the other people in the Alternate Timeline?
Ok, the ending reveals that the alternate timeline is not really alternate, but just a Lotus Eater Machine for the main characters to find each other again. Fine, that works. In the end, they all "move on" together. Ben decides to stay, but he is aware of where he is, and he may move on in the future. But what about everyone else? There were loads of people from the original timeline appearing in the afterlife. Are those the same people? Are they also waiting to move on, but haven't realized it yet? Or are they just figments of the main characters imagination and will disappear the moment Ben moves on? Together with the rest of the alternate universe? And if they are the same people, what about those who by now have died in both timelines, like Mikhail Bakunin or Keamy? Do they go to an alternate alternate timeline?
 * At least some of those people are implied to be real because the option existed for them to move on (ie: Ana-Lucia was described as "not ready yet" and Eloise begged Desmond not to take Daniel away from her). But others, like Jack's fake son David, are apparently just programs in the Matrix.

We're all putting way too much thought into this.
-This theroy is far too sane for the WMG list.

The ending suited the series perfectly.
Any answers they could have come up with for the questions we're left with would have been worse than just leaving the mystery and wonder, so they didn't even bother. They just kept goin' strong with the mind-screwin'.

The Man in Black killed Charlie.
The harpoon gun killed Mikhail. His body was quickly taken by the Man in Black, who took his form and blew open the window which led to Charlie's death. Alternatively, Mikhail really did die of a brain aneurysm when Locke pushed him through the pylons and the Man in Black took his form after that. Either way, the true Mikhail was dead by the time his body disappeared from the Looking Glass.
 * The Man in Black can't cross water, remember.

Sawyer went on to become a troper here on TV Tropes.
After all of his pop culture references, this is pretty much a given.

Richard becomes the mayor of Gotham after leaving the island.
He wants to help the world so he runs for mayor of a city that needs help. His familiarity of strange things is useful in his new job.

Richard, Miles, and Lapidus open a detective agency on Guam.
Lapidus made it to Guam, but brought Miles and Richard along with him. Miles used his diamonds to buy a building that they converted into a detective agency. Richard is the face, Miles is the brains, and Lapidus is the muscle. Together They Fight Crime! Hurley and Ben show up from time to time to act as magical Huggy Bears.
 * Call ABC and pitch this. I know I'd watch it.

The entire series is taking place in someone's mind.
Specifically, Jacob's. The Man in Black is trying to find the location of the cave of light.

The Man in Black escaped... as Lapidus.
FLocke didn't just turn back into normal, vulnerable Locke because of the light being turned off, the smoke monster had ditched him and taken the form of Lapidus, who actually died in the submarine explosion. FLapidus then stalled the repair of the plane until Jack was dead and took off safely into the sky, his passengers blissfully unaware that they were releasing a monster.
 * Then what the hell was Jack fighting?
 * Resurrected!Locke, obviously.
 * Then why was he so evil?
 * He was mad at Jack for not believing him.

Jack is an insane fugitive who hijacked and crashed the plane.
Jack is completely bonkers. He can't tell reality from fantasy and this gets a lot of people hurt. One day while on a plane being escorted to a remote island prison for such psychopaths by government agents James Ford, Edward Mars, and Ana Lucia Cortez, Jack escapes his bonds and forces the pilot to crash land on the island, giving him a chance to escape. He uses his Hitler-like charisma to draw a large following of other escaped prisoners to him while the prison warden, Ben Linus, tries desperately to recapture the fugitives. Ford is installed as an infiltrator in the prisoners' camp and lasts a long time without attracting attention, unlike his cohorts Ethan Rom and Goodwin Stanhope. Finally, with the help of a behavioral analyst (Juliet Burke), Ben is able to convince a schizophrenic prisoner named Michael to turn in the most dangerous of the fugitives. Jack and Kate are captured along with Sawyer (Still playing the part of Jack and Kate's compatriot.) and taken to the government prison, codenamed "The Hydra". A ruse is developed that the guards will kill Sawyer with an explosive pacemaker if anyone tries to escape, but there is no pacemaker, leaving Agent Ford safe from harm. While Juliet is interrogating Jack, she slowly starts developing Lima Syndrome due to Jack's aforementioned charisma. Jack organizes an escape from the prison and Juliet betrays the government agents, shooting one of the guards as the prisoners escape into the ocean.

the Lost ending isn't the real explanation.
It was a tv-show all along. Jack isn't REAL. He is played by an actor called Matthew Fox who used to be a model. So the ending doesn't count as actually JACK NEVER EXISTED. The island? HAWAII! The polar bears? CGI! Sawyer? Someone who also used to be a model. Kate? Played by a woman who used to be a model. The plane? Also a model.
 * "It's only a model." "Shh!"

The island is where the Earth is finalizing the Ultimate Question Of Life The Universe and Everything
Over its running time, the Earth has worked back from the Ultimate Answer of 42, to get the five Ultimate Intermediate Steps of 23, 16, 15, 8 and 4. Just a few more calculations are required to get the Ultimate Question right. It has been said that if both the Question and the Answer are known it will cause the Universe to disappear and be replaced by something much stranger - the proximity of the Answer to a preliminary version of the Question is causing that to happen on a smaller scale, leading to all the tropical polar bears, smoke monsters and Epileptic Trees.
 * This is simply brilliant. The final season of the series is obviously after the Vogons destroy it. The passing of the leader of the island to the next is actually simply allowing the hyper-intelligent, pan-dimensional being to inhabit another form. The island was built by the computer to keep the Golgafrinchams away from the main program matrix. )

The plot points that don't really make sense exist in seperate realities.
Any point where it looks like the realities overlap in a confusing way is only a hallucination experienced by one or several of the characters. Examples: The four-toed statue? The numbers? If were given viable explainations for all these, we'd need tons of actual "sideways" worlds and tons of flash-sideways with them.

Sayid survived.
We never see his body. Bomb or not, we never see any sort of remains. He will show up alive in the Spin-Off series and help Hurley, Ben, and Walt run the Island while Sawyer, Lapidus, Richard, and Miles run their afformentioned detective agency in Guam.

There is no Sickness.
The members of the science expedition, Rousseau included, were driven to absolute madness when Nadine and Montand were killed by Smokey, a creature they were unable to comprehend. Sayid and Claire were manipulated by lies and promises.

The Purge was ordered by Jacob as a test.
Ben and the Others failed. Richard was in on it and didn't actually participate.

Why certain characters weren't seen in

 * Walt
 * It's not a question of
 * Richard
 * Lapidus
 * Eko

The Light is not the source of life, it's the source of magic.

 * Magic exists in the world of Lost, and not just on the Island: Hurley sees dead people, Walt has his strange powers, Richard Malkin predicted the plane crash, etc.
 * The Island's Light is the source of all magic. Everybody has a little bit of Light in them, which connects them back to the source on the Island, and the people with more Light and stronger connections (i.e. Hurley, Walt, Malkin) are able to use it to perform miraculous feats.
 * The Island itself is imbued with the Light, to the point where the Light actually sustains the Island's existance (when the cork is removed and the Light goes away, the Island begins to crumble and sink into the sea). Because of this, all kinds of miraculous phenomena just natually manifest there, and everyone on the Island is affected much more than they'd ever be on the mainland.
 * As a result of taking on the job, the Island's Guardian has a stronger connection to the source of the Light than anyone else on the planet, so strong that he or she can effect people and events on a massive scale. He caused massive weather events to bring ships and planes to the Island, and he was so concerned with secrecy that he was able to shroud the Island and keep it hidden from the rest of the planet.
 * If the Light were to be destroyed or "uncorked" or whatever, it would basically eliminate magic across the entire planet. Nothing miraculous, no unexplained phenomena, nothing beyond the understanding of science. Whether or not that'd be catastrophic remains to be seen (it's possible that magic has something to do with the continued existance of the Earth, in which case, "uh oh"), but it'd sure make the world a bit more boring.
 * Mind you, there's some evidence that it's actually the force of life/death that Mother implies. Desmond's exposure to the Light in "Happily Ever After" allowed him to see the flashsideways universe, and in "The End", the light that Christian Shepherd releases into the church as everybody moves on has that same hue and glow as the Light from the cave. Maybe it's both, and magic in the Lost universe comes from the power of life and death?

All the ancient constructions (the pool, the cork, the statues, etc.) in the Cave of Light were built by Jacob.

 * In the commantary for "Across the Sea", Darlton heavily implies that the construction was done at some point between the events of that episode and "The End". Since it seems that only the Guardian has access to the cave, Jacob must have built it all, or at least directed someone to do it.
 * The reason he had this done was so that the Light would have an on/off switch and could be used exactly the way that Jack and Desmond used it in the finale. Tampering with the Light in its natural form would probably be very very bad, but installing the cork allows for the Light to be put out in a (relatively) safe, controlled way and then turned on again by replacing the cork. And surrounding the cork with raw light means that not just anyone can access it, only someone with Desmond's (Jacob-given) ability to withstand its power.
 * As Widmore touched on, this was Jacob's measure of last resort: if it seemed like the Man in Black was going to win and everything was in the toilet, the Light could be turned off, making the Man in Black vulnerable, and then turned on again once he's dead. The reason it's a last resort is because even this relatively safe, controlled release of Light causes the Island to start breaking apart within minutes, and there's only a small window in which to replace the cork before the Island sinks to the bottom of the ocean.

The Flash Sideways actually IS an alternate timeline.

 * But that reality hastily retconned itself into a quasi-afterlife because everything in it was going against its fate.

"The universe has a way of course correcting."

David is on his own journey of self-discovery.

 * The thought crossed my head while I was considering whether or not the 'extras' in the AU will move on in that world, or if they're just figments. But I considered the fact that David was obviously a rebelling teen character, and Jack was extremely worried that he ran away. Then it hit me; David did run away from home, and died without ever reconciling with his parents. He was paired up with Jack to see that even the most stubborn people can really care about you, and it's only a matter of time before David is reunited with his parents, and they all get to move on together.

In the LOST universe, there is only the earth and the moon.
You can see the sun, stars, other planets, etc in the sky - but the Earth is the center of the (very small, comparatively), universe. It is the Island which is operating and powering this universe, and removing the cork causes EVERYTHING to begin to break down (removing the cork was felt everywhere). Literally it would be the end of everything if the island was lost.

It wasn't the afterlife.
It was an AU where Un Locke was right, he kept his powers and the island was destroyed. People lie about the island's purpose and values a lot and when it was said that the Source was the light in everyone's souls, it was during a time when rationalizing things with deities and "magic" was commonplace. The Source was extremely powerful, but it wasn't a deadly world-destroying thing. Un Locke promises to have people meet with those who have died. He keeps his word as the island, once destroyed, moves everything one last time to the flash-sideways world(what Un Locke was actually promising). Now, what happened to Un Locke? I have two guesses: He ends up assimilated and fully becomes Locke or finally "moves on" himself by working for the island. As Desmond.

The Island is run by an invisible, Chaotic Neutral group of The Fair Folk.
In his essay, "On Fairy-Stories", Tolkien wrote that the realm of the fairies was "a perilous land and in it are pitfalls for the unwary" and that fairy tales might "be made a vehicle of Mystery". If those two things don't describe the Island, then what honestly does?

Thus these fairies are the real reason behind all the weird stuff happening on the island, and do everything for their own amusement. Sometimes this leads to helping people (giving Locke his ability to walk); sometimes this means hindering them; sometimes this means doing nothing if the humans are already doing something that they find inherently interesting (such as The Others attacking and killing the members of the Hanso foundation or killing the Losties); the main thing is to see how humans react to stuff for the sake of entertainment. Even helping people overcome their character defects is for this reason because they find the character growth interesting to watch.

Not even the protectors know about them, nor does The Man in Black.

Smokey the Human (pre-Un-Locke) was no more Esau/The Kid In Black than he was Locke (post-Un-Locke).
When he was Mode Locke'd, he gained mental and emotional attributes that Locke had. It's possible that he wasn't Jacob's brother, but rather just a thing that was present in the Heart of the Island that absorbed Jacob's brother's face, personality, and motive/drive. The reason he still wanted to destroy the Island after becoming Un-Locke is that he spent around a couple of thousand years wanting to get off the island, and Locke's primary reason for loving the island was that it was cool, and interesting, and had done a thing of beauty (restoring the use of his legs). Locke still liked the island, but the Smoke Monster/Man In Black didn't care about the spine-healing and couldn't reconcile his remaining positive views with its want to get off of/destroy the Island. It's quite plausible that it shared the MIB's want to leave the Island, and it may have even been the source of its/their want to destroy the island rather than just leave it. This guess is heavily backed up by "Esau"/MIB/Adam leaving a corpse, the same way Locke's corpse remained even though the Smoke Monster took on his face and attributes. See also "Jacob didn't create the smoke monster" above, which has the same base but runs a completely different way with it.

Jacob's brother was a nearly-successful Actual Pacifist, and could be trusted with guarding the Heart of the Island more than his brother could.
See the above guess(es) about him not really being the post-Smokeification Man In Black. When they were still alive, Jacob was far more violent than "Esau", and Mother wanted someone better than her, not the same as her, to guard the Source. That's why she prepared to die: Claudia's second son had turned out to be the perfect Candidate to be her successor.

Voldemum finished the donkey wheel.
Maybe she wanted a way to destroy all of the other people Out There who were bad for the Island and for her sons. She could kill an entire settlement and fill in a well while the Man in Black was briefly away, perhaps she could use her knowledge from being the Source's Guardian and the power that killed the settlers to fix the wheel. Perhaps she wanted a way out to Kill'Em All once her son took over her duty of guarding the Heart, but couldn't let herself leave until someone was guarding the Heart for her and Jacob's brother was safely stuck on the island.

Nothing was stopping anyone from coming back to the island once they turned the wheel, beyond what was stopping anyone else from coming to the island in the first place.
Ben decided to interpret it that way (maybe someone a long time ago said or wrote that it would be impossible to find the island again, since it was so difficult to find in the first place?), and nobody who knew otherwise bothered to correct his assumption. Ben came back, Locke came back (sort of), the polar bear died before it had a chance to be found and brought back. I don't know why the Man in Black would go to all the trouble of programming a no-return clause into the mechanism if it wasn't already there (unless he wanted to make sure his family couldn't drag him back), and I see no reason why it would have already been there.

The Island is on the Enterprise's Holodeck
Saw a Star Trek Next Generation episode with Terry O'Quinn, suddenly it all made sense.

The man Jack's first wife had an affair with was Sawyer
It would make sense, given his pre-island penchant for seducing and conning married women, and given the fact that his other romantic interests (Kate, Juliet, Ana Lucia) suggest that his numer one turn-on is women who Jack at some point wanted.