!!Jack
->Voiced by: PhilLaMarr

Our hero, a samurai and the son of the samurai who initially released (and then defeated) Aku. He trained in every country in the world in preparation for the final battle... only to be hurled into the future before he could land the killing blow. Now he must WalkTheEarth, seeking a way back to the past to finish that battle... not that this will stop him from setting things right in the future as well.

* AppropriatedAppellation: Calls himself Jack after some street kids refer to him as such.
* {{Badass}}: '''Very'''.
** BadassLonghair: Whenever his topknot comes loose.
** BadassLongRobe
** BadassNormal
* CelibateHero: He's got at least four valid motives for avoiding romance; it would distract him from his quest, he's a danger magnet, he'd have to return to the past, and he's been burned before. That doesn't stop the fangirls, though.
* TheChosenOne: Unbeknownst to him, he's going to be this when he's older.
* ChronicHeroSyndrome: He might be able to get home faster if he ignored the suffering of those around him. [[WhatYouAreInTheDark Shoot, because this future might cease to be if he succeeds, no one would ever know.]] But, if he were able to ignore the suffering of those around him, he just wouldn't be Jack.
* ClothingDamage: Seems to be a magnet for it after season one.
* TheComicallySerious: He does have a sense of humor and gets some witty one-liners, but these moments are few and far between.
* CompressedHair: Don't be fooled by that tiny ponytail. Once that pin's gone, you get some long, flowing locks [[{{Hammerspace}} that couldn't possibly make up that tiny ponytail]].
* {{Determinator}}
* TheDrifter: He doesn't stay in one place for long in his never-ending quest to return to the past.
* EvilKnockoff: Mad Jack, a being that was created from Jack's negative emotions.
* FishOutOfTemporalWater: A resident of the distant past trapped in the distant future. He's managed to adapt pretty well, all things considered.
* HatDamage: Whenever he wears one, it's usually the first thing to go.
* TheHero
* HonorBeforeReason: Which makes sense, since honor pretty much defines what a samurai is all about.
* IncorruptiblePurePureness
* KatanasAreJustBetter: Of course, the only reason being it was forged by the gods from his father's righteousness. It appears to be evenly matched with The Scotsman's sword, which was similarly mystically enchanted.
* LanternJawOfJustice
* MadeOfIron: Doesn't matter how intense the battle is. He always comes out of it alive, even if he's significantly worse for wear.
* MartialPacifist
* MosesInTheBullrushes: As soon as Aku attacked their kingdom, his parents sent him out of the country on a lifelong training mission and was raised by various different mentors in different lands.
* MrFanservice: Oh so much. He's even got some fangirls in universe!
* NiceGuy
* NiceHat: Sometimes wears one made of straw. Episode 26 reveals that he knows how to hand-weave a hat from the husks of straw, which explains how he always manages to procure replacement hats when they get continually pulverized.
* NoNameGiven: "Jack" is an alias he took in the future.
** NamedByDemocracy: It's what the first people he talks to call him and they introduce him as Jack to their friends... then Jack is put up on his wanted posters...
* OneManArmy: In the premier he takes down a whole army of killer robots by himself and wins, and in other episodes he routinely destroys multiple opponents at once.
* OnlyKnownByTheirNickname: Jack's real name is never mentioned in the series, not even by his parents!
** When Jack tells Ikra [[spoiler: (who, as Aku, is almost the only being in the future that ''could'' know Jack's name)]] that he is called Jack, her expression is priceless. [[spoiler: Of course, had she accidentally let slip his ''real'' name, she would have blown her cover right then and there.]]
* TheQuietOne: Usually speaks only a few lines each episode; some episodes he never speaks at all.
* RedOniBlueOni: The blue to the Scotman's red.
* {{Samurai}}: [[CaptainObvious Obviously]]
* SamuraiPonytail: Jack fits pretty clearly into the first variation of the trope with his noble attitude.
* SetRightWhatOnceWentWrong: Sums up his mission in life quite nicely.
* TheStoic: [[NotSoStoic Most of the time...]]
* TykeBomb: Non-evil example; Jack began training with numerous combat styles and many different warriors as a child, after he and his mother fled Aku's second attack on their homeland. Unlike most other examples, he was still brought up as a [[LawfulGood benevolent samurai with a code of ethics]].
** Flashbacks scattered thorough the series' run show that despite the rigorous training, Jack made many friends in the different countries he visited, played, and learned with the different people and cultures he met. Some people should take notes from this series on how to properly raise a OneManArmy.
* ShirtlessScene: Not so much during the first season, increasingly as the show goes on, almost qualifies as a WalkingShirtlessScene at some points.
* SlipknotPonytail: Also a magnet for this after season one (not as much as the ClothingDamage example, but it does happen).
* ThrowingYourSwordAlwaysWorks
* WarriorPrince
* TheWisePrince: He's actually a prince, and the day Aku appeared signaled the end of his sheltered childhood.

!!Aku
->Voiced by: {{Mako}}

Long ago, a single small fragment of an EldritchAbomination fell to Earth. Given form, it became Aku, a being of pure darkness and evil. When the samurai who would later be called Jack came to fight him, Aku hurled him into the future as a last-ditch effort to survive. In the future, Aku rules the world, and devotes a ''lot'' of effort to finishing Jack once and for all.

* BadBoss: You're probably safer as one of his victims than one of his minions.
* BadassBeard / BeardOfEvil
* BigBad
* CardCarryingVillain: Often refers to himself by several evil-sounding titles, just in case you couldn't tell he was evil by looking at him.
* CompleteImmortality: He hasn't aged at all since the day he was 'born' and heals from injuries almost instantly. The only weapon that causes him real harm and could potentially kill him is Jack's sword.
** Immortality aside, the episode "Jack and the Gangsters" shows it is still possible to at least overpower him and keep him at bay. The episode revolves around a MacGuffin called the Jewel of Neptune, a powerful artifact that even Aku himself is unable to seize due to the powerful elemental spirits guarding it. His numerous attempts to steal it have resulted in him getting his ass handed to him, and during the timeframe of the episode, he'd long since given up trying. Cue Jack [[TheInfiltration infiltrating]] a group of Aku-friendly mobsters and obtaining the jewel so he can be granted the opportunity to meet Aku face-to-face.
* EldritchAbomination: Spawned from the remains of a much larger one.
* EvilCannotComprehendGood: A large reason that his attempt to throw Jack into the future backfired. He'd expected a world ruled by him would allow him to crush Jack effortlessly when he arrived. He never took into account that a hero arriving and successfully fighting back his forces would trigger HopeSpringsEternal and start giving the oppressed masses someone to rally behind. Also shows when he tries to make himself out as the good guy in the stories he tells to children in one episode, one of the prime reasons it doesn't work is he didn't really comprehend what being TheHero actually meant.
** That episode teaches us that the closest Evil can come is to comprehend ''[[ItMakesSenseInContext free beef jerky for all!]]''
* EvilLaugh: "HAA HAA HAAAA!!"
* EvilIsHammy: Just the way he talks is so bombastic and over the top.
* EvilOverlord: Currently rules the whole planet and expanding his empire beyond.
* EvilPlan: The first one, take over the world, was over before the pilot ended. The one that drives the plot is his attempts to kill Jack, and, failing that, prevent him from traveling back in time.
* EvilSoundsDeep: As his voice actor once said, "Evil comes from the ''belly.''"
* EyeBeams: Multiple types for multiple purposes.
* FangsAreEvil
* FauxAffablyEvil
* FourFingeredHands: Considering he's great evil, [[FourIsDeath there's probably a meaning to it]].
* {{Jerkass}}: Fairly obvious as he is a villain, though he tends to swing back and forth between a comedic villain and truly evil one. Notable acts of evil include in the pilot episode when some aliens that lived an aquatic world whose oceans were dried up come to him requesting to live on Earth and reveals that he dried up their planet, though he does let them stay on Earth provided they build statues every month. Another note is when he forces a scientist to build a set super robots to kill Jack under the promise of sparing his village if does, and then tests the robots out by having them burn his village to the ground and kill everything in it.
* LaughablyEvil: He's rather... Goofy for being the Ultimate Evil and all.
** Varies depending on the episode, there are some that present him as legitimately evil and threatening figure. Or sometimes [[BewareTheSillyOnes a bit of both]].
* LargeHam: So hammy that one of the first things he makes his slaves do is build statues of him.
* MadeOfEvil: Yeah, that about sums it up.
* MeaningfulName: The word "aku" means "evil" in Japanese. It's also worth noting that he's the only major character in the series who is known by his real name.
* ObviouslyEvil
* SealedEvilInACan: Jack's father defeated him by sealing him away instead of killing him. The first episode shows him breaking free and taking his revenge.
* ShapeShifting
** MorphicResonance: He always has the same black, red and green color-scheme in every form he takes.
** ShapeshifterDefaultForm: Due to his origin it's hard to say if he's Type A or Type B.
** {{Sizeshifter}}: A natural extension of his shape-shifting ability, and in his default form he's usually gigantic. He tends to shrink whenever Jack's sword hits him, though.
** VoluntaryShapeshifting: He can transform into pretty much anything, and even introduces himself as a "shape-shifting master of darkness" during the opening narration.
* SpikesOfVillainy
* StupidEvil: He would actually have succeeded in defeating Jack many times over by now, if he could just resist throwing a VillainBall at the most inopportune time, [[KickTheDog he abuses]] {{Mooks}}, [[MistreatmentInducedBetrayal double crosses bargains]] or just spends too much time gleefully torturing Jack when [[JustShootHim he could easily crush him in an instant]], all ''just'' before the job is done. Jack's survival, and to extent, he and his sword's very existance, is owed to this happening time and time again.
** Aku's last resort to send Jack into the future as Jack was about to off him. If Aku can open a portal in time in this situation, surely he was strong enough to do something a little more fatal than that. Sure, Jack's stuck in the future, but fact is that ''he is still alive''.
* TakeOverTheWorld: He already has, but apparently it's not enough.
* ThirdPersonPerson: When he's being especially hammy.
* UnskilledButStrong: He relies mostly on the fact few things can actually hurt him. One of those is Jack's sword.
* UnusualEyebrows: "GREAT FLAMING EYEBROWS!"

!!The Scotsman
->Voiced by: JohnDiMaggio

A large, ''extremely'' loud Scottish man, with a sword inscribed with magic runes and a machine-gun false leg. He's about as burly a warrior as you'll find, and one of the few creatures able to match Jack for combat prowess. One of the few characters who appears more than once in the series.

* {{Badass}}
** BadassMustache
* BagOfHolding: The pouch on his kilt fit just about anything, including a hunk of gold as big as a boulder.
* BaldOfAwesome
* BerserkButton: Do NOT screw with his bagpipes. He might turn your head into a flour-shifter!
* BloodKnight: Unlike Jack, this guy really enjoys fighting.
* BraveScot
* BritishTeeth
* CarpetOfVirility: His head is about the only body part not covered in hair.
* EverythingsLouderWithBagpipes
* FieryRedhead
* GoodIsNotNice: In his case, it's downright rude.
* HeroOfAnotherStory: A [[LargeHam HUGE]] story!
* JerkWithAHeartOfGold: He absolutely adores his wife, and if Jack is in trouble he won't hesitate to help.
* TheLancer: He's the closest thing Jack has to a best friend in this world.
* LargeHam: He's the second most-wanted man on the planet and will brag about it endlessly.
* LightningBruiser: Despite being three times the size of Jack, he can easily match the samurai's speed to the point of them ending their fight in a standstill....three days later.
* ManInAKilt: And it's definitely not for fanservice.
* NighInvulnerability: When robot alligators bite his arms, he just laughs at them.
* NoNameGiven
* NoSell: In "Scotsman Saves Jack Part II", an amnesic Jack, the Scotsman, and a bunch of pirates sail the ocean, only to come within range of the song of {{Enthralling Siren}}s. Everyone on the ship becomes hypnotized, except the Scotsman. Why? The fact is that the song of the siren enchants men due to how beautiful it is to their ears. [[FridgeBrilliance The Scotman thinks their singing is horrible.]]
* RedOniBlueOni: The red to Jack's blue.
* TheRival: Friendly competition pretty much defines his relationship with Jack.
* SickeninglySweethearts: With his wife.
* SuperStrength
* ViolentGlaswegian
* WeaponOfChoice
** {{BFS}}: [[CoolSword A Claymore with magic runes.]] Not quite as cool as Jack's, but it comes close.
** LegCannon: A machine-gun! Doubles as GatlingGood.
** LikeCannotCutLike: Jack's sword fails to break his thanks to it having similar magical properties.

!!Jack's Father
The samurai lord who accidently awakened Aku when he tried to destroy the corruption he was otherwise unconsciously causing. The gods Odin, Ra and Vishnu forged the sword that would later become Jack's from his righteousness. He manages to seal Aku, until he returns once again to unleash evil. Apart from the first episode and the two-parter covering him awaking and sealing Aku, he mostly appears in flashbacks.

* AnnoyingArrows: Clearly disregards having been struck by some arrows during his fight with Aku.
* {{Badass}}
** BadassMustache
* CoolOldGuy
* {{Determinator}}
* TheEmperor
* IncorruptiblePurePureness
* KatanasAreJustBetter: Of course the only reason this one is better is because it's forged by the gods from his righteousness.
* LanternJawOfJustice: Apparently it's hereditary.
* NiceJobBreakingItHero: Nice job giving consciousness to a fragment of an EldritchAbomination.
* NoNameGiven
* PapaWolf
* ReasonableAuthorityFigure
* RoyalsWhoActuallyDoSomething: He's actually an emperor, but that doesn't stop him from charging into battle when his subjects are in danger. Now you know where Jack gets it from.
* PosthumousCharacter: Except for certain episodes that take place in the past, he's long dead in the present timeline.
* {{Samurai}}

!!X9
->Voiced by: DaranNorris

A retired, obsolete, prototype assassin android with emotions. He was blackmailed into targeting Jack, by Aku. Aku's leverage, he had kidnapped the one thing dear in the robot's life: His precious dog [=LuLu=]....sweet thing.

* [[spoiler: KilledOffForReal]]: [[spoiler: Inevitably, after a tension-filled confrontation, Jack catches X9 while his back is turned and runs him through. Because X9 refused to back down for the sake of Lulu, Jack had no choice but to finish off X9 before the robot did the same to him. X9's final request was for Jack to find his precious Lulu and take care of her before he went offline for good.]]
* ABoyAndHisX: Inverted. A Robot and his Dog.
* AntiVillain: [[SlidingScaleOfAntiVillains Type II.]] Depends on how you view his mission.
* BadassInANiceSuit: You have to admit, this robot has style!
* FailureIsTheOnlyOption: The series isn't named ''Robot Assassin X9... and Lulu.''
* FilmNoir
* ForcedIntoEvil
* GlowingMechanicalEyes
* GunsAkimbo
* HeroicBloodshed: The bot may have been serving a greater evil purpose he was still only trying to save his dog.
* JustAMachine: Possibly averted due to Jack's reaction after X9 muttered his dying words.
* LastOfHisKind
* MoreDakka: Of the pistol variety. Only once do we see him actually taking a accurate shot.
* PersonalityChip: His greatest strength and a biggest flaw.
* SlidingScaleOfRobotIntelligence: Average Joe Android. What he lacks in social skills he makes up for with musical ability and love for his dog.
* SugarAndIcePersonality
* SuperPrototype: Thanks to his emotion chip. In a way it was a prototype within a prototype.
* TrenchCoatBrigade
* WhatMeasureIsANonHuman

!!The Guardian
->Voiced by: KevinMichaelRichardson

A powerful warrior that guards a time portal, waiting for TheChosenOne to find and use it. When Jack finds the portal, he is told by the Guardian that he's not the one, leading Jack to try and beat him anyway.

* AlwaysSomeoneBetter: Has Jack's ''number'' in combat.
* AmazingTechnicolorPopulation: He's blue.
* {{Badass}}: Being one of the only characters in the series that actually ''beats'' Jack in battle has to count for something.
** BadassInANiceSuit: He's very fond of his suit too.
* BaldOfAwesome
* BeefGate: A rare example outside video games.
* BerserkButton: Never, ever ruin his suit.
* DualWielding: First dual wields [[http://en.wikipedia.org/wiki/Sai_(weapon) sai]], then switches to dual wielding firearms.
* GunsAkimbo: One a machine gun, the other a machine gun[=/=]rocket launcher.
* HaHaHaNo: This is his response to Jack's request to use the time portal.
* [[YouAreNotReady He Is Not Ready]]: Is told this about Jack after their battle.
* HyperspaceArsenal
* JiveTurkey: Has shades of this.
* LightningBruiser: Much like the Scotsman, he is able to match Jack's speed despite being much larger than Jack.
* MultiMeleeMaster: Expertly uses [[KatanasAreJustBetter a katana]], sai, and eventually his fists.
* [[MyFavoriteShirt My Favorite Suit]]
* NighInvulnerability: Missiles don't as much as scratch him.
* NoHoldsBarredBeatdown: His battle with Jack slowly turns from an even match to him on the giving end.
* NoNameGiven
* [[TheOnlyOneAllowedToDefeatYou The Only One Allowed To Defeat Me]]: Claims that TheChosenOne is this, and is therefore the only one that will use the time portal.
* RedEyesTakeWarning
* ShoutOut: His appearance, usage of a Katana, and the way Jack is reflected in his eyes are all reminiscent of Morpheus from Film/TheMatrix
* SuperStrength
* TennisBoss: Subverted; Jack thinks he can beat him by bouncing his missiles back at him, but he's sadly mistaken.