Samurai Jack/WMG

Samurai Jack is a Future Imperfect retelling of Inuyasha

 * Aku is Naraku, and Jack is a composite of Kagome and Inuaysha. Jack's sword is therefore Tessaiga. As the tale of Inuyasha was passed down from generation to generation through oral tradition, the specific details got lost or mixed-up, and Inuyasha and Kagome eventually merged into a single character. As time further progressed, the credibility of a story involving someone going back into the past to fight demons became lost, but a story about someone traveling into the future from the past to fight robots, while not necessarily more credible, was of greater interest to a society not only becoming more technologically savvy but simultaneously increasingly suspicious of their technological dependence and somewhat pining for simpler times. Thus, a nameless warrior bestowed with the nickname "Jack" sent into the future to fight the robot hordes of Naraku (by now simply shortened to "Aku") who had also become a more exaggerated, simplified version of himself.

Aku is Nyarlathotep

 * Aku was created from a part of some kind of Eldritch Abomination that was defeated by various deities. Nyarlathotep is the soul of Azatoth, the blind idiot god. It's hinted that Azatoth wasn't always mindless as he is now, but his current state is the result of being defeated by the Elder Gods. Aku is a shapeshifter. Nyarly has a thousand different forms. Aku takes over the world in the future. Nyarly seems to be plotting his way to world domination (altho he also plans on destroying mankind). Both are immortal godlike beings, virtually immune to normal weaponary. However, while the Great Old ones and Outer Gods are immortal, it would still be possible to destroy Nyarlathotep's physical avatar with a powerful enough weapon. Jack's sword, being blessed by the Elder Gods is a weapon cabable of doing this.

Jack is not in the future nor has he ever traveled through time

 * Jack's father warns him that evil's greatest weapon is deceit. Aku in a desperate bid to escape certain doom casts a spell on Jack. Think which would be easier; sending Jack to the future OR making Jack believe he is in a distopian future where failure is the only option. The entire series is taking place within a few seconds after the first battle with Aku, it just seems that long due to Jack's perspective. The entire point of the future "world" is to break Jack's spirit by taunting him with victory only to snatch it away from him at the last second. It's only Jack's determination that makes it appear like good ever triumphs in the dream world Aku painted for him. In a particularly cruel twist, Aku is using Jack's own pride and determination to trap him in this comatose state. As long as Jack is determined to find a way back to the past, he's doom to remain a pawn in Aku's game. Only by giving up the quest and realizing the facade can he escape the spell and awaken to defeat Aku.
 * Alternatively, traveling back in time will represent Jack waking up.
 * A different alternative, Jack could have been under an illusion that, instead of speeding up his perception and lasting only a few seconds, he's viewing his family and friends as enemies from the future, and every time he's attacked Aku with a potentially letal strike, it was an illusion placed over one of his most trusted associates.

The true ending of Samurai Jack...

 * Jack figures out that he's a person from the future who used his latent psychic abilities to make himself a new body in the form of a samurai from his vivid dreams, and also subconsciously created Aku the same way. It ends when he blows up a large city to kill Aku's forces and miraculously survives. Why? Read Ronin.

Jack did not travel through time.
The spell merely put him into suspended animation, possibly in an invisible/intangible state or pocket dimension. Either way, there's no going home for him.
 * Unless... Shaolin Showdown's history arc was made to provide a crossover ending for the show, and Jack Spicer: Evil Boy Genius is going to use his portal to the past to save the day.

Jack is unconsciously preventing his success.
There have been several opportunities for Jack to get back, but he always ends up staying to help someone else. He's realized that if the timeline included his victory then Aku would no longer be around. Since Aku still exists in the future that mean Jack either failed to ever return or died in the past before he could defeat Aku. Since Jack doesn't want either to happen, he finds ways to justify staying. The scene that shows an older Jack making it through the portal (a vision Jack never got to see) happens after Jack decides to Screw Destiny or someone explains to Jack the concept of alternate timelines.
 * Possibly, he wants to destroy the Aku in this time before he goes back to destroy the one in his home time, just to make sure that the future has hope too.
 * Or Jack knows about Alternate Timelines and therefore thinks going back in time will leave this future intact, so even if goes back and defeats Aku, the Aku in the future will still be alive, so he's waiting to go back until he defeats this Aku first.
 * More grimly, we don't know for a fact that Alternate Timelines are possible in the world of Samurai Jack, and though he isn't a physicist or sci fi buff, Jack may well realize this (at least subconsciously). So, if he goes into the past and kills Aku there, he may end up erasing everyone in the future from existence. Even if it saves millions of people suffering in the present/past, Jack will probably justly feel uncomfortable at the prospect of unmaking everyone he's befriended in the future.
 * Alternatively, Jack doesn't know any of that, but is consciously preventing his success because either a) his success will cause/allow someone else to suffer a fate which Jack could prevent, which he knows he could not live with on his conscience or b) he feels he isn't ready to return: if Aku snatches/destroys the portal at the last second, then it is proof to Jack that he isn't strong enough to defeat Aku in the past. Aku (both past and future), on the other hand, DOES know about the implications of time travel, and is saving the "killing me will negate the future you fought so hard to protect" bombshell for when Jack is about to kill him a second time.
 * Alternatively alternatively maybe--despite all his talk--Jack honestly doesn't believe he can defeat Aku. That "You were prepared to sacrifice. I was not." line fits with this: he doesn't want the monks to die to send him back unless he's damn sure it won't be in vain.

Jack is Aku.
What, don't look at me like this! There's a possibility that Jack got corrupted by himself, thus, creating a Time Paradox and putting so many different timed and placed characters in an unique setting. Jack/Aku just had ripped the fabric of Time and Space apart, somehow or another. First hint is his true name never being revealed. Maybe The Scotsman went through some rip and is the true hero, as he'll save Jack from being corrupted through Power of Friendship.
 * This unregistered troper went to this page expecting to see just that. He was not displeased. I think that maybe Aku is Jack Evil-Side (that was created by Aku in a episode). Maybe when Jack walks through a portal (or before that), he will be divide into two forms. He "normal side" and his "evil side". While his "normal side" manages to return to the past to defeat Aku, his "evil side" manages to return to the beginning of time (maybe by the use of some really powerful Black Magic and turns into the giant black mass that is shown in the beginning of the story.

Aku is the Unreliable Narrator of the series.
In one episode, Aku reads fairy tales to children concerning some of Jack's adventures. Why not the whole series? Nothing else about it makes much sense.
 * It makes enough. Enough to suspect that it's a better storyteller than Aku: the kids. AND THEN THEY FIGHT!
 * Possibly, he is reading the story after he's been defeated, and is being self-depreciating.
 * Maybe the comedy episodes are told by Aku to the children and then the more serious episodes are told by the parents to their kids as a way to give them hope to the future. The adults know that there isn't a strong enough warrior to defeat Aku, but they can't say that to the kids so they make up stories using the warrior from the stories. That's also the reason Jack never manages to go back to the past. Because if the parents told the kids that, then they would be wandering "Why isn't the Great Big Fun Leader Aku destroyed?" which would make the kids know that their parents are lying about the whole thing.
 * So, in the show's reality, Jack doesn't even exist, he's only a legendary/mythical hero made up by the enslaved population and mocked by Aku? Hey, I like this.
 * I've been wondering about this for a while and find it pretty likely. Just think about it... The whole series begins with the rebirth of Aku. He tells the opening narration. Jack, his entire family and friends don't even have names because Aku simply doesn't care about human rubbish like individuality. Even if he doesn't actually telling the stories to someone, the events could be seen from his viewpoint. This seems to be more likely to me because it could explain why do we see Jack as a positive hero: even if Aku lies about him to the children, he cannot lie to himself.
 * Or alternately, He DID send Jack to the future, he just hasn't arrived yet. Aku is telling stories of a legendary hero predestined to arrive in order to crush them completely when he kills Jack when he arrives...only it'll backfire and give Jack an army ready, willing, and able to help bring Aku down.

Jack can't return home until he's defeated Aku in the future.
If he returns to the past and defeats Aku there, the future will likely still exist as an alternate timeline, to be tormented by Aku for eternity. Jack will not be allowed to travel back until he destroys Aku in this time too, to give hope to the future as well as the past.
 * Alternatively, Jack will only be allowed to return home once Aku is dead simply because Aku won't stop finding new ways to screw Jack out of reaching a working portal until one of them dies.
 * Alter-alternatively, by Jack killing Aku in the future, he will have no problems defeating Aku in the past, as Aku's powers and influence seem to have gotten stronger over time. In other words, Jack killing Future Aku means he'll defeat a stronger opponent than Past Aku, thus Past Aku won't be as hard as a fight as his Future self - basically, Aku will, himself, have accidentally given Jack the training he needs to beat him in the past. Yeah, Mind Screw I know.
 * Not so far fetched. DBZ's Future Trunks did the exact same thing. By the time the Cell Saga was done, he had enough power in his own time to effortlessly dispatch Androids 17, 18 and Pre-Transformation Cell. Jack will know all of Aku's best tricks before he does. Maybe the sword was forged with a mental suggestion that Aku send his foe fwd, and the slashing transmitted the suggestion. Odin and his homies know how to play Aku.

Jack's sword is a nexus of Spiral Power.
Even gods needed to use something within the human spirit as raw materials. By extension, Aku is related to the Anti-Spirals. Then there's Robo-Samurai...
 * Why does using spiral energy lead to Aku being associated with the Anti-Spirals? Although I can certainly see generating enough spiral energy to destroy him attracting their attention...

Aku is the spawn of Erebus
In the backstory, Aku emerges from a great darkness. The previous rulers were the Titans. Erebus in Greek mythology was the primordial darkness. It makes perfect sense. Of course, this means that it is likely false...

Jack is Insane
Jack was never sent to the future. Rather, he was born in the future, and being one of the best warriors in the world, decided to create a persona with which to fight Aku. However, living in the dystopian future has driven Jack completely insane, and caused him to believe his own back story as a way of disassociating himself with a reality he hates. The rest is history.

Jack never Existed
The entire series is a series of stories told by the parents of the children in Aku's future to give them hope. Jack never existed, and Aku rules unchallenged forever.
 * A grim but very interesting idea which would make Jack kind of a religious figure.
 * Explains how Aku is a Card-Carrying Villain, too: If Jack is a Jesus figure in Purgatory, that makes Aku a Satan figure. Odds are that we're only seeing one side of the story, and a version actually told by Aku paints Jack as a Well-Intentioned Extremist at best.

Jack will be battle his way Backwards in time
It goes like this: Jack ended up finding a way to go into the past, but only a few hundred or thousand years. With a so long to go back, he will be forced to defeat Aku each time, slowly removing the stain of Aku as he goes until he can destroy him at the source, appearing in the time when Aku was either an unthinking darkness or trapped in the tree.

Aku is made of Chemical X
Also Jack is one of Professor Utonium's ancestors.

Jack's sword is a zanpakuto
Why the hell not? "Aku: "And now, foolish samurai, your journey homeward ends!" Jack: "That is correct. Expunge the inky stain of darkness, Hikari. Bankai. Tenshi no Hikari. Tsubasa no Yamigoroshi."
 * The ending:
 * giant sphere of light wipes out all Akus that ever existed*"

The ending of one episode is out of chronological order...
Which episode, you ask? The one where he learns to jump good. The episode ends with Jack jumping into the air, to attack Aku, who is holding what looks like a portal to the past. Ok, I know it's unlikely that by the end of the series, Aku won't know about Jack's ability to jump good...but damn it, I want to believe we have a canon resolution to the series.

Jack won't return to his own time
Assuming we get the movie this time, Jack will have two options He can return to his own time and fight Aku, or he can fight Aku in the present. At first, he'll be on his way to do the latter, but will realize that either A) the future world he's currently living in will still exist, and that Aku, having learned this, will actually change his mind about time travel, and ENCOURAGE Jack to do this, or B) The future world will cease to exist, as will all the people he helped, some of whom will never even have evolved due to the lack of Aku. Ultimately, he'll decide that, however tragic the enslavement of his people, and Aku's reign over Earth may have been, they aren't worth abandoning/sacrificing the future for, and he'll ditch his last chance to go to his past to have an epic final battle against Aku, and completely destroy him. The last clip we'll see is Jack's allies celebrating the defeat of Aku, and Jack smiling sadly, and walking away. Cue tears

Aku is Chase Young is Him
After Aku sends Jack into the future, Aku starts gleefully taking over the world but for what ever reason will take on a diferent form and start calling himself Chase Young. Why? Who knows, maybe he get's bored so takea a new form or maybe he becomes someone diferent depending on who he is fighting, the Japanese get Japanese monster (This Troper knows very little of Japanese mythology), Xiaolin Monks get Chase Young, Christians get Him. Regardless, what I am trying to say is that many shows (preferably just Cartoon Network ones) are all linked by one super natral monster. Aku/Chase/Him.

Samurai Jack is a graphic novel written by Buttercup and drawn by Bubbles after they grow up.
It would explain the previous reference to Townsville and the Talking dogs in the beginning, Jack's similarity to Professor Utonium, and why Aku seems like Chemical X personified. And if Bubbles was drawing, it would explain why every enemy Jack cut was a robot, and makes a lot of sense with the silent episodes as when the two had creative differences.

Aku is active during the Powerpuff Girls' time, and is the ruler of Monster Island
So we know from that there's an actual place called Monster Island. Said island is, in fact, the PPG's version of Japan, still ruled by Aku, who has somehow been constrained to its borders since he conquered it in Jack's time. So, for the time being, he makes do creating monsters and sending them to do battle in the outside world, waiting for the moment for the stars to be right or something along those lines. Eventually, as we can see from the ruins of Townsville in Jack's first episode, it does.

Jack will stop Aku in the Future and Past
But he'll learn that there are hundreds, if not thousands of alternate dimensions. Driven by his desire to ensure that no one ever suffers Aku's terror, Jack will find a means to endlessly travel time and space, fighting Aku for all eternity. Yea, definately a bit of a downer ending, but it would show how bad ass Jack is if he were willing to sacrifice any chance of peace just to ensure that Aku never exists in any dimension.
 * Jack's not immortal
 * You say that like he actually cares. If he realizes his own mortality, he'll find a successor, or have a son.
 * Besides, this is Jack we're talking about. He can jump good and fight armies and only get a little winded. Who's to say that Jack might not be able to live to be a Badass Grandpa whose Really 700 Years Old?
 * Potentially canonically possible, even, given Jack and the Monks - one of the monks from his own time manages to survive until Aku's future through sheer spiritual adeptness.
 * I could agree with the first idea, only a little bit TMNTized. Jack will find Aku prime, where Aku is the original form of himself, and through all the powers he has obtained will rape Aku with his sword. The reason he remains to fight this particular Aku is to test his ability with the most powerful foe he has ever faced, so that he can be a steel trap whebn it come to Aku prime.

Time travel double time!
Jack will travel back in time to just a few minutes before he is sent forward. Then past jack and future jack will team up against Aku, where he will manage to send past jack to the future
 * Wouldn't that fuck with his memories of when he was sent to the future? Way I see it, that could happen, but then Future Jack will return to the ruined future that he fought so hard to protect, and his only reason for returning to the past was to create a timeline that had a shining future.
 * That wouldn't be a Stable Time Loop, because it would be different than what happened in the original timeline.

Aku is the personification of all primal fears
It's obvious.
 * GREAT FLAMING EYEBROWS symbolizes the fear of extreme heat and fire itself. Almost any being of an intelligence above that of a bug realizes that fire is dangerous, and automatically fears it.
 * The dark, opaque body represents the fear of darkness and the unknown. Intelligent life forms are usually wary of being trapped within the dark, completely defenseless and unwary to any threats.
 * Aku's penchant for grabbing things in his massive claws resembles the innate fear of being trapped in a small, restricting space.
 * Aku's mouthful of teeth and many forms symbolize the fear of large, powerful beasts with massive claws and rending teeth.
 * His magic powers represent the fear of beings much, much more powerful than you, and of mysterious nature. Think of the fear that, say, a native American felt when a colonist or soldier shot him. To him, this humanoid that looks kind of like him, but at the same time entirely different, just pointed a metal stick at him, releasing a massive noise, a cloud of smoke, and an immense feeling of pain within the poor native's body.

Jack has in fact traveled through the portals
But with Aku being a trickster not one has successfully sent him to the correct time, and most simply sent him to different places not far in time to let Aku prepare better. This is a pretty optimistic view of the series meaning jack has beaten Aku more times than what we have seen.

Aku will be killed by a Combined Energy Attack
Jack, in the final battle, will call for aid from everyone he's befriended in the entire series and lead them into a Final Battle with Aku (makes sense as they can help make sure Aku can't escape this time and deal with his minions). During the final battle, Jack is nearly defeated but all his allies (or possibly the entire planet, odds are Aku would broadcast the battle to the entire world to crush them if he won) transfer their rightious spirit into the sword (which was forged from rightiousness, thus can be powered by it). Jack then uses it to completely obliterate Aku in one attack.

Jack will return to the past...after training the Scotsman to kill Aku
The Scotsman is Jack's equal with a holy sword as well. So he teaches the Scotsman everything he knows to give him an even better chance and allowing him to destroy Aku once Jack returns to the past, giving the future a hero.

Aku won't be killed in battle but instead suffer a Villainous BSOD
Jack realizes physically attacking Aku can't destroy him, but figures out a way to copy his moral personality into Aku. With a conscious, Aku suddenly is overcome with guilt for several eons of causing pain and suffering across the universe and begs Jack to finish him off. Seems like something jack would do.

Jack's father actually made things better instead of worse
Alright, Jack's father is the one who gave Aku sentience and a physical form, yes. But while this may seem like a Nice Job Breaking It, Hero, it may have actually changed the situation for the better. Think about it, the formless evil that became Aku was slowly spreading out from where it landed, consuming all in its path, possibly consuming the entire planet if given enough time. By giving Aku a physical form, it changed Aku's intent from destruction of everything to conquest. Yes, the world under Aku's rule sucks, but at least it can support life and people, and animals, have somewhat adapted to it. Along with that, Aku's new form is fightable, dangerous and powerful, but something that can be outwitted and fought instead of simply destroying everything in its path. So despite apparently worsening the situation, Jack's father may have in fact improved it.

Aku's humanoid form is simply a type b Shapeshifter Default Form
He remains in it because its easier and he can maintain control. His true form has a drawl back that makes it not a good idea (like losing the sentience he obtained from Jack's father's arrow) and he's saving it for a One-Winged Angel transformation in the final battle (if we ever see it).

Ikra is not another personification of Aku, she is Aku's daughter
She is Jack's oppisite, not unlike Ying and Yang. She is both good and evil, she got the evil from her father and the good from her mother. In fact, Jack has to turn her against her father in order to finally defeat Aku. She may even be Jack's soulmate.

If the show continued, Jack would have been a Tragic Hero
Also, his weakness, his fatal flaw, would be a love of the fairer sex. In at least one episode, Jack was almost stolen away by a beautiful fairy woman. In the same episode, multiple enemies came and Jack took care of them easily, but the beautiful woman he almost fell for. I also recall another episode featuring a female bounty hunter who almost seduced him. If the show continued, Aku would have taken the form of a beautiful woman to trick Jack.
 * Unless I'm misunderstanding something, that's already happened in season 1.

The Scotman's sword is Soul Eater Excalibur.

 * From the United K. He's Lookin' for Heaven. He's goin' to CaliforniaGethbot (talk)

Aku took over/made the Instrumentality
The dogs in the first episode are Underpeople, and many places Jack visits are taken from different eras.

"Jack" is in purgatory
He will never make it home, but will forever being haunted by it's closeness, being literaly in his grasp (the episode where he rescued a fairy, from a gargoyle, that could wish him home). He can never be killed, he's forced to walk an eternity as an invincible person constantly wanted by the authorities (the episode where his own sword could not be used to kill him, in the hands of evil. His god is vengeful for him letting AKU go. I beleive it will all end with his god picking him up on the final day of his purgatory, and hurling him for eons more into time where he will land before The Great and Powerful AKU, stripped of his defenses and skills, and will be used how his new lord sees fit.
 * And yes I do admire AKU, his color sheme, his voice, his wretchedness. If anyone should enslave the human race I'd be glad for it to be him.
 * Ia Ia

The Scotsman's Wife is a descendant of Amy Pond.
It explains so much.

The Eldritch Abomination that Aku was a piece of was Amatsu-Mikaboshi.
Because that would probably make the battle even more epic.

Da Samurai is in fact Afro Samurai
This means that Justice and Empty Seven either serve Aku, or else are being manipulated by him, and (no surprise) the video game is Discontinuity.

Jack is in fact in Phyrexia.
A world of machines that bleed oil ruled by an ancient evil?

The Scotsman is in the same situation Jack is.
Either shortly before or shortly after Jack first attacked Aku, the Scotsman attacked and nearly defeated Aku with his magic sword. To avoid defeat, Aku simply threw the Scotsman into the same future Jack is. Since his machine gun leg is a somewhat modern weapon, Scotsman might have gotten his leg removed and replaced while he was in the future.

When the movie is finally completed, in the finale, Jack's real name will be revealed to be Mako
Because that would be just too perfect an homage to give the late actor who voiced Aku so spectacularly.