History Characters / SamuraiJackAku

* MaouTheDemonKing: A shapeshifting demon ruler born from a pit of evil in Japan who commands legions of demons created from his evil essence, and whose defeat is needed for the time displaced Samurai to complete his journey and save the world. Aku's face is even based on the Japanese ''{{oni}}''[[spoiler:and it would later be revealed that Aku has several beautiful daughters, including Ashi.]]

* WeHaveBecomeComplacent: A villainous example. In the earliest points of the series, Aku has been unchallenged for years, and thus fails to take Jack as a threat too seriously, wasting multiple ideal opportunities to get rid of him by toying with him, grandstanding, or otherwise pulling a VillainBall. Even his keen ability to dupe Jack into traps flounders as Aku gets lazier and more overconfident in Jack's gullibility. It is only after these many failures compound, and he realises Jack not only won't DIIIEEEE but isn't even aging, that Aku starts to feel the weight of the situation he is in; and that he might be stuck hiding and duelling with Jack ''forever''.

* MaouTheDemonKing: Played completely straight.

* OverarchingVillain: Basically, he is the catalyst for the whole series.

** Season 5 reveals that Jack's {{ageless| immortality}} nature is due to Aku sending him to the future. Aku later decided to destroy all known time portals to deny him all hope of returning home, but while this is debilitating to his nemesis, his immortality has ensured that Jack could potentially be a thorn in his side ''forever''.

* BotanicalAbomination: Though Aku is normally characterized as being a creature of dark alien essence, there's a lot of wood and tree motifs to him. When he was a non-sentient pile of goo he attacked with sharp tree-like spikes. His horns resemble branches, his essence twists and deforms itself into an evil-looking tree when the Emperor seals him away, his joints creak like wood, and during his confrontation with the Scotsman, he even calls Aku a tree-demon. Plus, his standard form is tall. Really, really, tall.

* BotanicalAbomination: Every movement of his body makes sounds like wood fibres stretching and snapping for some reason.

* VileVillainSaccharineShow: A meta-example. While Aku isn't the first Creator/CartoonNetwork BigBad who's an absolute monster with no redeeming qualities (i.e. [[WesternAnimation/CourageTheCowardlyDog Katz]]), he is still one of the darkest Cartoon Network villains to date, which is quite impressive. He's a sadistic, genocidal dictator, with his crimes being heavily centered on mass murder, slavery, torture, MindRape, and other acts of inhumanly extreme cruelty. Compared to the more friendly, cartoonish, and laughable villains, Aku truly sets this series apart from Cartoon Network's other shows. No wonder why the final season of the series became part of Creator/AdultSwim.

* FanNickname: Jacku/Jaku.

* EldritchAbomination: [[DownplayedTrope A bit watered down]] compared to the the run-of-the-mill versions. While his origin is completely Lovecraftian his [[EvilIsHammy demenor]] [[EvilIsPetty is]] [[ForTheEvulz less]] [[PsychopathicManchild so]]. Like many Lovecraftian entities, he can take various forms according to his intentions but Aku himself is actually very human in his motivations and thinking. In spite of being an abomination that's MadeOfEvil, Aku's only desires are to cause pain and suffereing and rule the universe like a king. He's basically demonic version of [[Franchise/FlashGordon Ming the Merciless]].

* TakesOneToKillOne: As a magical entity, Aku is immune to conventional attack and can only be harmed by magic. Divine magic in particular, such as Jack's sword, are his kyrptonite.

->''"[[WhoDares Who dares]] to summon the Master of Masters, the Deliverer of Darkness, the Shogun of Sorrow, '''Aku?'''''"

** Greg Baldwin more closely matched Mako's later take on Aku as Season Five progressed, initially being far more baritone and having a peculiar accent.

* EternalVillain: Aku is essentially one of these and has been the prime source of evil many good characters have fought against one way or another over the years. He born from the Evil Primordial Mass that fought the Gods when it tried to consume the cosmos, fought Jack's father when he first tried to take over the world, and continued to antagonize Jack himself from that point on. Jack's travels through the future reveals Aku fought many other heroic figures such as the Lava Monster while Jack was away and put them into horrible punishments upon defeating them.

* TooPowerfulToLive: It was so powerful that the ''TopGods themselves'' from '''''[[UpToEleven three separate pantheons]]''''' had to fight it personally!

* TheSociopath: Despite being a demon that is literally made of pure evil, Aku has the classic traits of a psychopath. He is exceptionally adept at putting on a good facade of trust; He is entertaining, bombastic and funny ([[FauxAffablyEvil superficial charm]]), he possesses an inordinate attitude of superiority and grandeur, destroys cities and commits crimes to satisfy his sadism and tendency to boredom, is a [[ConsummateLiar pathological liar]] who frequently deceives and manipulates for personal gain, or even ForTheEvulz; He's incredibly aggressive with things related to his ego, and perhaps most importantly: he possesses an incredibly high criminal versatility, with atrocities that could take up more than one sheet, which is quite common in sociopaths/psychopaths.

* NightmareFuelStationAttendant: He manages to bring us a fair share of NightmareFuel in "The Premiere Movie". His hissy CreepyMonotone, his lack of humor and absolute sadism and cruelty...

* KarmicDeath:
** [[spoiler:Aku meets his end when the daughter he turned into a living weapon and tried to kill Jack with takes Jack back in time, allowing him to destroy Aku's past self and erase him from existence.]]
** [[spoiler:Past Aku is killed when Jack returns from the future 50 years stronger and more experienced, allowing him to annihilate Aku. Doubly so as Aku dies exactly the same as the many innocents he killed: terrified for his life against a foe so much stronger than he is that there is nothing he can do about it.]]

* EvilIsPetty: Despite having higher goals and ambitions, Aku cannot resist committing [[KickTheDog unnecessarily cruel and petty acts]] to people he's already screwed over, often to prove he can or just for a sick kick at their expense. He ends up taking it to StupidEvil levels as he ''always'' backstabs anyone he makes a deal with, just to laugh at their misfortune.

* DarkIsEvil: In addition to being mostly black, his primal form is nothing but a billowing dark mass.

* CharacterizationMarchesOn: In the pilot episodes, he's actually quite a fairly serious, ominous antagonist, lacking a lot of the dark sense of humor that would characterize him later on. Aku was also [[ColdHam much quieter, though still dramatic]]. In the episodes showing how he was born, his personality is as serious as in the pilot episodes, which indicates that the timeskip changed him greatly.

* YourSizeMayVary: Possibly justified given his shapeshifting, but even then his size varies from shot to shot. Most of the time, he's 5 times the size of a skyscraper, others he's only a few stories tall.