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The main heroes group. The TMNT with their master, Splinter.
As a whole
- Airplane Arms: The turtles consistently run like this.
- Le Parkour: Unless they run like this.
- Badass Family: The turtles and Splinter, undeniably so.
- Bald of Awesome: By virtue of being hairless reptiles.
- Color-Coded Characters: In the Mirage comics, the Turtles all wore red bandanas (not that it mattered much in a black-and-white comic), leaving their distinct weapons as usually the best way to tell them apart. The series follow the '87 choice of give Leonardo blue, Donatello purple and Michaelangelo orange, while Raphael kept red. Lampshaded in Turtles Forever when the Mirage Turtle call "silly" both the '87 and 2003 versions for this.
- Five-Man Band: The Turtles including their allies
- Foil: All four of them as a group and in pairs
- Red Oni, Blue Oni: Raph and Mike are Red, Leo and Don are Bluenote
- Foolish Sibling, Responsible Sibling: Mikey > Don ~ Raph > Leo
- All Work vs. All Play: Leo and Mike
- The Hero vs The Lancer: Leo and Raph
- Brains and Brawn: Don and Raph
- Hypocritical Heartwarming: Raph towards Mike
- The Smart Guy vs Book Dumb: Don and Mike, sometimes played as academic intellect vs (pop) cultural awareness.
- Spirituality vs Science: Leo and Don, but they're both levelheaded enough to defer to the other's expertise so they usually don't have any real tension when they pair up together.
- Four-Temperament Ensemble: Leonardo the phlegmatic, Donatello the melancholic, Raphael the choleric and Michaelangelo the sanguine.
- Future Badass: Leonardo, Raphael, April, and especially Mikey, in "Same as it Never Was".
- Happily Adopted: The Turtles love and respect Splinter as if he were their real father.
- Highly Visible Ninja: They can frequently be seeing putting around on a blimp. With a giant "Turtles" on it.
- Not to mention the Turtle Van, which was customized with armored plates resembling turtle shells and laser turrets on the roof.
- Know When To Fold Them: The Turtles sometimes invoke this, with Raph on one occasion settling on a "tactical retreat". This is also the Ancient One's first lesson, when a bitter Leo faces a losing battle against intangible demons.Leo: To surrender is not the warrior's way!The Ancient One: You won't be much of a warrior without a head!
- Metamorphosis: From turtles to humanoid turtles.
- Named After Somebody Famous: They are all named after iconic Renaissance artists.
- Ninja: They are ninjas.
- Trademark Favorite Food: Though pizza is the favorite food of all four turtles, Michelangelo eats it more obsessively than the other three.
- True Companions: Badass Family plus friends.
- Undying Loyalty: The turtles to Splinter.
- Weirdness Magnet: Noted several times:Michelangelo: How come all the weird stuff always happens to us? I mean, we were just minding our own business, when WHAM, that time lady fell out of the sky, right on top of us! Now we're stuck here AND we've gotta go to that creepy-loking place! It just doesn't seem fair!!!
- Would Hit a Girl: The Turtles have no problems with attacking Karai, although to be fair, she is more than capable of holding her own in a fight.
- Voiced by: Michael Sinterniklaas
- The Ace
- Authority Equals Asskicking: Consistently the most skilled Turtle, he falls into the leadership role by default.
- Badass Longcoat: In "Same As It Never Was".
- Big Brother Instinct: Even though he's never officially stated to be the oldest.
- The Chains of Commanding: Michaelangelo actually notes this in an episode of the 4Kids series: Leo takes the burden of being the leader so his brothers can do what they want: Dontaello's free to pursue his technological inventions, Raphael's free to let loose and fight, and Mikey's free to just relax because their brother's in control.
- Character Development: Really beautifully put into the mix in season 4 where Leonardo becomes the best fighter of the bunch while trying and failing to master his anger and fear after being defeated and stabbed in season 3.
- Cultured Warrior: If one of the turtles is going to be in touch with Japanese traditions, it's gonna be Leo.
- Deconstruction: A minor one but in Samurai Tourist, Mikey—yes, Mikey— gives an accurate analysis as to why Leo takes the burden on being the leader: so that he lets his brothers be themselves.Mikey: I think you all [Donatello, Raphael and Casey] should just lay off the poor guy [Leonardo]. I mean, it can't be fun always being the responsible one. And we're the ones who really benefit: Raph's free not to think cause Leo does all the thinking for him, Don's free to dream, and I'm free to take it easy all because Leo's busy being responsible enough for all of us.
- Dual Wielding: He always wields two swords, and if one is broken he still fights with the other one.
- Emotions vs. Stoicism: A lot of what he puts up with has him wondering if he should fight or remain still.
- Heroes Prefer Swords: As the leader of the group, Leo gets the shiny swords.
- Heroic B.S.O.D.
- Heroic Spirit: A big reason why he's a determinator.
- He's Back: Happens to Leo twice: First during "Return to New York", when he confronts the Foot Elite which nearly killed him during their first encounter, and again in "Prodigal Son", the conclusion to his season 4 character arc.
- Heterosexual Life-Partners: With Miyamoto Usagi.
- Katanas Are Just Better: Obviously. Although Leonardo's swords are often much more closely modeled around the ninjato.
- Knight Templar: Leonardo's story arc in the 4th season have him nearly cross over into Knight Templar territory. His rage gets so bad he actually wounds Splinter and has to be sent away to Japan to learn from Splinter's master.
- Master Swordsman: He uses his katana very skillfully.
- My God, What Have I Done?: Leonardo has an example of this in "The Ancient One", when he loses control and injures Master Splinter. Although he doesn't actually say the line, the look on his face after it happens and his subsequent remorse show he was clearly shocked, and deeply regretted his actions.
- No-Holds-Barred Beatdown: He gets into quite a few of these. If he's not on the receiving end, he's usually administering it.
- Red Oni, Blue Oni: The blue to Raphael's red.
- Samurai: Leonardo is technically a ninja, but a lot of the tenets he quotes are in line with samurai. It's no surprise he and Usagi got along swimmingly.
- Scars Are Forever: To an extent. In the Season 3 finale, Karai—whether accidentally or not—stabs Leo. Her sword goes through his shoulder and out the side of his upper shell. All throughout Season 4 the crack in his shell remains as he descends into Knight Templar territory, and even after he recovers it refuses to heal. Not until the Fast Forward reboot, anyway.
- Sliding Scale of Idealism vs. Cynicism: He starts out at the very end of the Idealism scale, even believing the best of the Shredder and then his daughter Karai. As the seasons progress he shows signs of being capable of sliding down the other way—he does this in the fourth season—though he remains mostly rooted in idealism.
- The Spartan Way: Leonardo as a child was suffering from a fear of heights. Splinter brings him to the top of a gigantic reservoir and pretends to be in danger of falling. Leonardo forces himself to crawl out and save him, and apparently conquers his fear in the process.
- Took a Level in Badass: In the first season he can barely handle fighting one of the Foot Elite, and is nearly killed trying to take on all four. By the end of the fourth season, he not only takes on all four without apparent difficulty, but also bests Karai, the incumbent Shredder, in the process.
- Took a Level in Jerkass: During the first half of the fourth season, combined with Heroic B.S.O.D.. He had a really good reason.
- Weapon of Choice: Twin Katana.
- What the Hell, Hero?: In a reverse from usual situation, Raph calls Leo out in 'The Ancient One' for injuring Master Splinter when Leo loses control in a fit of rage.Raphael: Leo, what the shell is your problem?!
- Wrecked Weapon: Done to Leonardo's swords in the episode "The Shredder Strikes Back, Part 1", as the climax to the ass-kicking the character gets in that episode. And again in "Big Brawl, part 1" by a Gom-Tai.
- Voiced by: Sam Regal
- Badass Bookworm: He's an Omnidisciplinary Scientist par excellence as well as a skilled warrior.
- Badass in Distress: The time he was captured by the Triceratons, and the end of the Outbreak arc after being mutated a second time. Less dramatic instances are scattered throughout the 4Kids series, too, usually when it would be easy for him to solve a problem/end an episode before its time.
- Badass Pacifist
- Beware the Nice Ones
- Beware the Quiet Ones
- Big Little Brother: Taller than Leo but, fittingly, tied with Raph.
- Bond Breaker: Donatello was warped into an alternate future where he had disappeared for 20 years. Without his resourceful, tech savvyness, the Turtles were disbanded and the Shredder had succeeded in world domination. The supporting cast made up the last rebel resistance.
- Fighting from the Inside: A variant while he was prisoner on board the Triceraton mother ship, resisting against borderline Mind Rape. He held out for awhile, but needed help to fend the assault off.
- First-Person Smartass: Whenever he's the one voicing the opening narration.
- Future Me Scares Me: One episode of the Fast Forward season has a future journal suggesting that robot butler serling might be Donatello's future self. Donnie and his brothers are grossed out by the idea. Fortunately, the journal is a fake set to discourage the turtles from trying to learn too much about the future.
- Gadgeteer Genius: Considering that he's self-taught, living in a sewer, and working mostly with scavenged junk, Don's inventing abilities are downright super-reptilian.
- Genius Bruiser
- Gentleman Snarker: He's second only to Splinter where polite snarking is concerned.
- Heroic B.S.O.D.: Like Leonardo, he suffers one in the 4Kids series' last season up until the end of episode 5. Cody finally manages to fix his Time Window to send the turtles and Splinter back to the present, but due to some inteference from Viral, Splinter is vaporized and it's later revealed that he's trapped in cyberspace.
- Intelligence Equals Isolation: Not often, but on occasion he's sequestered off in his lab. Most noticeable in 'Return to the Underground'.
- The Klutz: A trait that doesn't come up often— but if/when it does, it's always in the middle of a fight or stealth mission.
- Lovable Nerd
- Metamorphosis: Twice— once in the backstory, once at the end of the fourth season.
- Mr. Fixit
- Nice Guy
- Omnidisciplinary Scientist: He's a genius mechanic, but usually also has knowledge of biology.
- O.O.C. Is Serious Business: Played backwards, actually. We get the 'serious business' part within the first few minutes of Same as it Never Was. Just before the episode's Bittersweet Ending, the OoC part comes in.
- Out-of-Character Moment: Don absolutely slaughters Ch'rell at the end of SaiNW, a far cry from his usually pacifistic actions. Understandable, of course given the circumstances.
- Precocious Crush: He has one on April.
- The Professor
- The Reliable One
- Resist the Beast: Happens to Donatello in "Adventures in Turtle Sitting". He even begs April and Casey to "stay away from" him as he runs off, before he mutates fully and starts to attack them.
- Sesquipedalian Loquaciousness: Donatello, being the smart turtle, is particularly fond of this. A notable example is in "The Shredder Strikes Back, Part 1", when he and Raphael are watching a football match on television.Raphael: 'Panthers', 'Rams', 'Bears', they even got 'Dolphins'. You'd think they'd have room for something a little more...reptilian.Donatello: The 'Turtles'? My friend, unfortunately the lowly turtle has been saddled by society with the stereotype of being velocity challenged.Raphael: Say what?
- Teen Genius
- This Is Unforgivable!: In "Same as it Never Was", after stating a Big "NO!" upon watching the Karai Legions kill Future Mike to his horror, Don gets pushed too far. His response? "You'll pay for this, Shredder! If it's the last thing I do, YOU WILL PAY!"
- Weapon of Choice: Simple Staff.
- Weirdness Magnet: Even amongst his brothers.
- Wrong Genre Savvy: Demonstrated a couple of times — like trying something he saw in a movie during a fight with the Foot. It doesn't work.
- Wrecked Weapon: Donatello's bos were constantly getting broken. One wonders why he never upgraded to a steel pole or something a bit sturdier.
- Voiced by: Frank Frankson
- Aloof Big Brother: Partially inverted. He's younger than Leonardo making him an aloof little brother, but older than Donatello and Michelangelo, playing it straight for them.
- Badass Biker: He is shown to be a skilled motorcyclist and has his own motorcycle, the "Shell Cycle".
- Bash Brothers: With Casey.
- Berserk Button:
- He loves his bike and quickly turns to rage if anyone messes with it.
- Did we mention how much Raph hates bugs? In "April's Artifact", he gets pushed too far after recovering from the paralysis given to him by one of the hornets, declaring in a Punctuated! For! Emphasis! fashion that bugs must pay.
- Big Brother Bully: To Mickey.
- Big Damn Heroes: In the "City At War" arc (with some help from Splinter).
- Brooklyn Rage: Not only because he's an angry New Yorker - the first movie even gives him a Brooklyn accent.
- Catch Phrase: "I got your X right here." and also "You and me are having words."
- Deadpan Snarker: To the point where he should be the picture for the trope.
- Driven by Envy: Downplayed. Raphael appears to live in the shadow of Leonardo and resents his brother's social position in the group. However, though at times he may seem quite jealous of Leonardo, Raphael's rivalry with him is heavily toned down in comparison to the comic books, and Raphael rarely shows a deep hatred towards Leo as the series progresses.
- Fire-Forged Friends: With Casey
- Hair-Trigger Temper
- Heel Realization: In "City at War part 3".
- Jerk with a Heart of Gold: He's more abrasive than the others, but is still as noble as the other Turtles.
- Jerkass Façade
- Jerkass Has a Point / What the Hell, Hero??: Raph's attitude during the "City at War" trilogy. What the Hell, Hero? stems from the fact that he refuses to believe that the Turtles were responsible for New York's gang war between the Foot Clan, Purple Dragons, and the Mob and he sounds like he doesn't care about the innocent people who have been caught in the crossfire. This stems from his statement that the Turtles' involvement would only "add fuel to the fire", in other words, make the situation worse and to be honest, Raph wasn't wrong; apart from Leo saving a gang of mobsters from an exploding warehouse and evacuating a man trapped in a bus, the Turtles weren't making much progress to end the war until Karai showed up and offered a truce.
- Middle Child Syndrome: Played with. Raphael isn't the middle turtle, but he feels as if no one understands him.
- Number Two
- Red Is Heroic: He's always a hero but typically in on-going series he plays the lancer to Leo while in one-off stories he is the main protagonist who has to overcome this anger.
- They Really Do Love Each Other: Despite sometimes being a jerk to his brothers, Raphael is very protective of them.
- This Is Unforgivable!: Raph doesn't take too well to having been paralyzed by one of the hornets in the episode "April's Artifiact".Raphael: Bugs... must... PAY!
- Throwing Your Sword Always Works: Raph throws his sai a lot.
- Took a Level in Kindness: It's more so "losing a level in jerkass", but by Back to the Sewers, Raph was no longer beating up Mikey or challenging Leo's authority, though he still flung a few insults here and there and even those were reduced.
- Weapon of Choice: Sai Guy.
- What the Hell, Hero?: In "Meet Casey Jones", Leo and Don call Raph out when he loses his temper and almost attacks Mikey with a metal pipe.Leonardo: Raphael! Have you lost your mind?!Donatello: You OK, Mikey? What were you thinking, Raph?!
- Why Did It Have to Be Snakes?: A running gag throughout the world of TMNT is Raphael's fear of bugs (entomophobia). However, in this carnation, it is less a phobia, and more of an intense hatred and disgust
- You Have Got to Be Kidding Me!: Raph loves using this.
- Voiced by: Wayne Grayson
- Arbitrary Skepticism: Michelangelo is the first to encounter Leatherhead, and when he tells them, the rest of the Turtles disbelieve him. At this point in the series, they have already encountered/know the existence of ninjas, criminal organizations, superheroes, cryptids, aliens, and mystical forces, yet a giant crocodile (mutated in the same way they were) is unbelievable.
- Attention Whore
- Badass Adorable: Silly, loves him some comic books, childish, always willing to crack a joke and and can kick tons of asses with his nunchucks.
- Beware the Nice Ones
- Beware the Silly Ones
- Big Eater: He'd often annoy his brothers by eating all the pizza.
- Brilliant, but Lazy: He's usually portrayed as having great potential, but because of his more laidback personality, he'll focus on something more fun instead.
- This is enforced with his Weapon of Choice (the chucks, see below), the laziest of the turtles is the one wielding the most complex and difficult weapon. That's not something one can do without a gift for it.
- Butt Monkey: If any of the Turtles klutzes out or has something bad happen to them for comic effect, it's Michelangelo.
- Catch Phrase: The most famous "Cowabunga!"
- Character Development: Michelangelo finally grows up, begins to use his innate skills to his full potential, and proves his worth as a thoughtful member of the team.
- Cloudcuckoolander: Generally the most whimsical of the turtles.
- Crouching Moron, Hidden Badass: In Michelangelo's first centric episode, he becomes a superhero, saves another superhero, and during all this learns a lesson on why he's a ninja: because it's what he does best.
- In "Touch and Go", Splinter tells him that he is the most naturally athletic of his brothers and he is crowned the winner of the Battle Nexus on a technicality (although with Leo's training, he wins outright in "Grudge Match").
- Friend to All Living Things: He has had several pets in the past, including his pigeon Pete and his parrot Ditto.
- Fun Personified
- The Heart: Although he exasperates his three brothers on a constant level, when a serious rift between their bond takes place, he usually is the one to try and patch things up...usually via humor.
- Hidden Depths
- Hooks and Crooks: He uses one briefly as a callback to precendent show.
- Jumped at the Call
- The Knights Who Say "Squee!"
- Large Ham
- Leeroy Jenkins: He doesn't usually think of a strategy before heading into battle.
- Nice Guy: Genrally is the most friendliest, most outgoing and most soft-hearted of the Turtles. Howewer, sometimes, he borders on Adaptational Jerkass).
- Plucky Comic Relief: He got this role in the show and held onto it throughout all other incarnations.
- Pungeon Master: Michelangelo, much to his brothers' continued annoyance. He constant puns almost always trigger negative reactions from his brothers, ranging from groans, Facepalms, and derogatory looks, to outright physical punishment such as head-slaps, flicks and pulling the ties of his ninja mask. His brothers aren't immune to it either: on the rare occasions when one of them says a bad pun they'll almost always get a similar Lame Pun Reaction from another turtle, though it's typically not as aggressive as the reactions dished out on Mikey.
- Real Men Wear Pink: In Back to the Sewers he was positively delighted when April asked him to be her Maid of Honor, when people tried to call him the more gender-neutral "Turtle of Honor" he would correct them.
- Screams Like a Little Girl
- Secret Identity: Turtle Titan.
- The Slacker
- Surfer Dude: Less compared to Fred Wolf cartoon.
- Unsportsmanlike Gloating: Michelangelo's preferred method of handling victory.
- Weapon of Choice: Fighting with Chucks.
- Voiced by: Darren Dunstan
- Adaptation Dye-Job: Splinter's fur is turned gray for this series.
- Adventure Rebuff: Splinter tries this several times, unsuccessfully.Splinter: How many times have I told you not to sneak out to the surface?Michelangelo: This month?Donatello: Five hundred and twelve, actually.
- Badass Grandpa: He's much older than the Turtles, but is still a capable fighter when he needs to be.
- Big Good: He and the Ancient One take up the role in the back half of the fifth season.
- Bow and Sword, in Accord: Splinter is armed in this manner in the first episode of the "Exodus" two-parter.
- Butt Monkey: He sometimes finds himself on the receiving end of his sons' antics.
- Cool Old Guy: Sometimes joins the Turtles in their pastimes.
- Deadpan Snarker: Fans tend to agree that he has some of the best lines in the show.
- Elemental Rock-Paper-Scissors: How Splinter defeats the Foot Mystics during their initial battle.
- Gentleman Snarker
- Gratuitous Japanese: Splinter will occasionally use this.
- Koan: Splinter is fond of these. Subverted on one occasion when he had to explain what he was saying.Splinter: Remember, my sons, even the mighty oak bows before the raging storm winds.Mikey: Huh?Splinter: Be careful and do not become overconfident!
- Not So Above It All: He loves his soap operas, beats out Casey and Raph in poker several times, snarks periodically about his sons' antics, and even cracks a joke here and there.
- Old Master
- Offhand Backhand: When the Shredder and the Foot Ninja attack April's antique shop, Master Splinter smacked a Foot Soldier with his stick without even turning back. He does this again to another Foot ninja when Karai invades the Lair and maybe once more at one point in between.
- Overprotective Dad: Not just towards the turtles but also towards April, Casey, and Cody (who also has Serling).
- Papa Wolf: He will not take kindly to anyone who harms his four students.
- Parents in Distress: For all of the times Splinter has rescued his sons, he has to be rescued by them often as well.
- Rodents of Unusual Size
- Simple Staff
- Sophisticated as Hell
- Team Dad
- Voiced by Veronica Taylor
- Adaptation Dye-Job: April's hair is given a purplish tone.
- All Girls Want Bad Boys: April is shown to have an attraction to Casey Jones, though their contrasting personalities often make them bicker.
- Badass Bookworm
- Bare Your Midriff: April initial outfit includes this, and is in fact apparently considered appropriate attire for her job as a lab assistant.
- Battle Couple: With Casey, eventually.
- CoolBigSibling: April and Casey, who are 23 and 24, respectively, at the start of the series, are this to the teenaged turtles, who're supposed to 15 at the start of the series and about 18 or 19 at the end.
- Hot Scientist: Just as in the Mirage comics, April started out as a 23-year-old science assistant to Dr. Baxter Stockman before he went openly evil.
- Letting Her Hair Down: Inversion: If April's hair isn't in her trademark bun the situation generally isn't good.
- Mission Control: This version of April makes much more use of her scientific expertise and she often uses her computer skills to aid the Turtles.
- Not So Above It All: Most notably in "April's Artifact" where she gets waaay into the Jungle Princess role and "The Christmas Aliens" where she sticks a spoon on her nose and grins stupidly.
- Took a Level in Badass: In season 3, when Splinter teaches her martial arts.
- Unfazed Everyman: After her intial scream and/or faint upon meeting the turtles she becomes this.
- Waif-Fu: April sometimes demonstrates martial arts skills, after being trained by Splinter.
- Voiced by Marc Thompson
- Badass Normal: The only member of the team who has never had any mutant powers or abnormal origins in any continuity.
- Bash Brothers: With Raph.
- Battle Couple: With April.
- Batter Up
- The Berserker: Initially.
- Big Damn Heroes: Gets to do this occasionally
- Boisterous Bruiser
- Brooklyn Rage
- Catchphrase: It's revealed that the young turtles were teaching him all about martial arts and fighting (although they never found out) and each took turns to teach him what they knew. The cry comes from when Mikey was training him and told him to say "Gorogoro-sama!" (translation: Lord Thunder). But since Casey couldn't pronounce it correctly, he made his famous phrase.
- Combat Pragmatist: Even the bad guys admit that Casey just plain fights dirty.
- CoolBigSibling: April and Casey, who are 23 and 24, respectively, at the start of the series, are this to the teenaged turtles, who're supposed to 15 at the start of the series and about 18 or 19 at the end.
- Dark and Troubled Past: Casey's hatred of crime is rooted in this incarnation in his childhood. While Casey was still a kid, his father Arnold Casey Jones, Sr. refused to pay protection money to the Purple Dragons. His father's shop was burned down as a result, and a teenage Hun threatened Casey to tell his father to pay up next time. Despite being threatened not to, Jones, Sr. subsequently went to the police, but with no success; it is implied that the Purple Dragons later killed him for trying to turn them in.
- Embarrassing First Name: Arnold. Casey is his middle name, nickname, or derived from his middle initials (K.C.) depending on the incarnation.
- Fire-Forged Friends: His friendship with Raphael consistently begins this way, and leads him to befriending the other turtles.
- Good Is Not Nice: In his debut episode. He gets better though.
- Heroes Want Redheads: Casey Jones with April O'Neil. The series even takes their relationship all the way as by the final season, they get married. April herself was much more of an obvious redhead than any previous incarnation as well.
- Improbable Weapon User: Hockey sticks, baseball bats, golf clubs, croquet mallets, cricket bats...
- The last being really amazing because you gotta know what a crumpet is to understand cricket!
- I Know Madden Kombat: Casey uses sports equipment as his main weapon.
- Jerk with a Heart of Gold: All versions have him being a jerk to at least one of the heroes, but they all still have a heart.
- Mask Power: When going into action, Casey usually wears an old-style hockey mask.
- Overshadowed by Awesome
- Took a Level in Badass: Casey undergoes a bit of this in Back to the Sewer when training under Master Khan (he manages to sneak attack and take down all four of the Turtles in this episode) but brainwashing is involved and the show doesn't give any strong indication of whether he retained his newfound fighting skills afterwards.
- However, Casey still applies to this trope as it was revealed that when he was young, Casey lacked the confidence he shows as an adult, until the Turtles trained him to be assertive.
- Vigilante Man: As he grew older, Casey became a vigilante and started hunting down crooks — particularly Purple Dragons — in the streets. until he meet Raph.
- You Gotta Have Blue Hair: Has black-blue hair.
- Voiced by F.B. Owens (Season 2-3), Gary Lewis (Season 4-BTTS)
- Adaptational Intelligence
- The Berserker
- Emotional Bruiser: This versionn was quick to show off just how tender-hearted he is in addition to how tough he is.
- Genius Bruiser: Here he is not only intelligent but also well versed in various technical and scientific fields and therefore the Turtles and their friends (including Professor Honeycutt) find not only his giant strength but also his great intelligent helpful.
- Metamorphosis: From alligator to humanoid alligator everywhere else.
- My God, What Have I Done?: Leatherhead says this almost word for word when he attacks Michelangelo in a fit of uncontrollable rage, leaving him unconscious and fearing him badly hurt/dead. Don't worry though; Mikey was fine.
- No-Holds-Barred Beatdown: In "Exodus, Part I", Leatherhead finally comes face to face with the Shredder. Enough said.
- Sewer Gator: He was a pet alligator that was flushed into the sewers before he was mutated.
- Unexplained Recovery: Hun and Leatherhead both appear to fall to their doom in "Exodus, Part 1". They both appear later with no explanation of how they survived or what happened to them immediately after the episode. Granted, their fall was indoors and it is rather hard to determine how far they fell (and unlike the Gyoji, it is rather doubtful that the writers intended this to be their death).
- You Can't Go Home Again: Leatherhead initially yearns to rejoin the Utroms.
Professor Honeycutt/The Fugitoid
- Voiced by Pete Zarustica
- Badass Bookworm
- Brain Uploading: The most commonly accepted explanation for his existence, although doubts are eventually raised as to whether this is the case.
- Just a Machine: Although it's not true, he is considered this by The Federation.
- The Professor
- Voiced by
- The Ditz: Renet is shown to be quite a scatterbrained person who came to her friends with good intentions, but with little practical skill she caused some problems across space and time.
- Forgotten Phlebotinum: She's completely and inexplicably absent from the Fast Forward season, where the Turtles are stuck in the future — because if she'd appeared she could instantly have fixed their predicament.
- Most Common Superpower: She is notably endowed as well.
- Nice Job Breaking It, Hero: Already in her first appearance, Renet was sentenced to dusting in Lord Simultaneous library because she had accidentally reversed the evolution on a planet of giant worms, and got a six-week penalty. Quickly, she tried to use the Time Scepter to get though her sentence quickly. However, this played into the hands of Savanti Romero, who caused the arrival of the scepter with black magic.
- Time Police
- True Blue Femininity: Her outfit is mostly blue and it matches her Innocent Blue Eyes.
- Valley Girl: Her speech is this.
- Voiced by Jason Griffith
- Bash Brothers: With Leonardo. The two became very fast friends, and Usagi even goes to the point of calling Leo brother during "The Real World" parts one and two. It helps they have the same weapons and that Usagi's just a more cynical version of him.
- Crossover: The characters and setting of Usagi Yojimbo show up more than once in the series, and "Across The Universe" features Raphael in one of Peter Laird's other stories, Planet Racers.
- Gratuitous Japanese:
The Foot Clan
The Foot Clan
An ancient order of shinobi, assassains and spies dating back to medieval Japan. In present day, they have semi-independent chapters all over the world, overseen by the japanese head council.
- Avenging the Villain: The Foot are honor-bound to avenge the death of The Shredder, but agree to void the blood debt if the Turtles assist in bringing order to the New York branch.
- Conservation of Ninjutsu: Ridiculously prone to this.
- Cyber Ninja: The Foot Tech Ninja, which grants them invisibility.
- Faceless Mooks: The rank and file ninja have virtually no defining characteristics.
- Ninja: They're generally ninjas, trained by Shredder.
A high-ranking member of the Foot Clan
- Ambiguously Evil
- Anti-Villain: Rarely holds any enmity towards the turtles, fighting them on Shredder's orders.
- Avenging the Villain: Her motivation for fighting the Turtles after they defeated Shredder.
- The Bad Guy Wins: "Scion of the Shredder" has Karai seemingly killing Master Splinter and all but one of the Turtles (Leo), as well as destroying their lair. By the next episode it's revealed that they all survived, however.
- Broken Bird: In seasons 4 and 5.
- Co Dragon: After her introduction, she shares the role of The Dragon with Hun.
- Corrupt Corporate Executive: Once she takes over her father's enterprise.
- Daddy's Little Villain: She actually is the Shredder's foster daughter.
- Dark Action Girl: Can usually take any one of the turtles head to head, though not all four like Shredder frequently can.
- Demoted to Dragon: Originally in the comic, Karai was a Foot Clan commander on the same level as the Shredder, sent by their mutual commanders in Japan to clean up his messes.
- The Dragon
- Dragon Ascendant: In season 4. After Shredder's defeat she takes the mantle for her own.
- She reassumes her role as co-dragon in Turtles Forever.
- Enigmatic Minion
- Evil Counterpart: To Leonardo.
- Good Colors, Evil Colors: A very subtle one occurs with Karai in Season 4. Normally she wears pink lipstick, but for "Prodigal Son" she wears red lipstick, symbolizing her crossover into evil when she believed she's killed the Turtles. After Leo defeats her the next time we see her she's gone back to the pink lipstick, showing she's not so evil and such a threat anymore.
- Heel–Face Turn: Though it doesn't happens until season 5.
- Holding Hands: Karai does this to Chaplin at the end of Season Five.
- Honor Before Reason
- Hooked Up Afterwards: Karai and Chaplin, after the season 5 finale hand-holding.
- Lady of War
- My Master, Right or Wrong: This is the struggle that Karai faces in the second and third seasons whit her loyalty to her adoptive father, The Shredder, clashes with her more noble instincts. One of the forms this clash takes is in her reluctance to kill the turtles, who had agreed to help her restore the New York Foot in exchange for ending the syndicate's vendetta against the turtles. While the agreement was made under false pretenses—it was made under the assumption that the Shredder was dead and that Karai would be leading the Foot, which Karai knew was not the case—she still felt compelled to keep it, despite her father's wishes.
- No, You: Karai's not very good at trash-talking. She does this several times to the Tengu Shredder.
- Red Eyes, Take Warning
- Shoulders of Doom: As Shredder.
- Spikes of Doom: As Shredder.
- Tin Tyrant: When she takes over the Shredder's mantle.
- Tykebomb: An orphan found and adopted by the Shredder at an early age, he turned her into one of his most loyal and capable lieutenants. The Shredder, surprisingly enough, turns out to be a rather good parent (at least from her account) and the ensuing loyalty she feels to him is at the core of her character arc.
- Undying Loyalty: This is what prevents her to make a Heel–Face Turn for most of the series; She genuinely respects the Turtles, almost has a friendship with Leonardo and knows to some extent that the Shredder's motives aren't exactly pure, but due to the role he played in her life, she feels like she owes him, and stays by his side no matter what. Even when he actually is defeated, she ends up blaming the turtles for it and going on a Roaring Rampage of Revenge against them. Eventually, it takes the Shredder trying to destroy the Universe (him and her included) to make her leave him once and for all.
- Villain with Good Publicity
- Wild Card
- Worthy Opponent: To the Turtles in general, but typically to Leo.
- Hideously mutated clones of The Shredder, dressed in modified Shredder armor and trained to work as elite Foot soldiers.
- Big, Thin, Short Trio: Shiva-Shredder is huge and hulking, Claws is thin and lean and Shrimp is short.
- Body Horror
- Fragile Speedster: Owing to his size, Shrimp is incredibly fast, but not as strong as the others.
- Lean and Mean: Claws is notably slimmer than his "brothers".
- Multi-Armed and Dangerous: Shiva-Shredder has four arms, each equipped with shredder claws.
- Elite ninjas of the Foot and the Shredders personal body guards and lieutenants.
- Avenging the Villain: After the Shredders death at the hands of the Turtles, the remaining Elites swear a vendetta against both them, and the factions of the Foot now fighting for control over New York.
- The Dreaded: Becomes this to Leonardo after the savage beatdown he recieves at their hands. They are not present in the comic book version of the storyline.
- Elite Mook: I They serve as the absolute best fighters of the Foot, second only to Shredder himself.
- Enemy Civil War: They strike at all parties involved in the war over the New York underworld, including the Japanese Foot.
- Flat Character: None of them really have any character traits beyond their blind loyalty to the Shredder. In the cartoon each Elite has a unique weapon, an axe, a spear, a poleaxe and a doublebladed sword, but thats about it.
A young scientist who becomes the head of the Foot's science department in season 3.
- Amazon Chaser: A look at his Amazon Blade Bots makes it clear that a large part of his crush on Karai rests on her ability to kick ass.
- Improbable Age: Although the art style makes it somewhat hard to determine just how old he is, the various comments made about it suggest that he is either a teen or barely in his twenties when he debuts, which makes him a rather young for a doctor and way too young for a department head.
- Punch Clock Villain
A highly skilled Foot Ninja who tries to bring the Clan back to its former glory in season 7, and who becomes Cyber Shredder's agent in the real world.
- Animal Motif: The dragon—fitting, since he's also The Dragon
- Convenient Replacement Character: Essentially only introduced in Back to the Sewers to replace Karai as the acting leader of the Foot, since it's heavily implied that she left with Chaplin after the season 5 finale
- The Dragon
- Evil Mentor: He is first seen running a martial arts school, whose students include Casey.
- Flat Character: He doesn't serve much purpose besides being the Shredder's right-hand man.
- A New York street gang consisting of mostly teenage thugs, thieves and killers.
- Ascended Extra: Like the Shredder, the Purple Dragons were one-shot characters that appeared in the very first issue of the comic book, though unlike the Shredder, it would be decades before they became a permanent part of the Turtles rogue's gallery.
- Starter Villain: The very first opponents the Turtles fought.
- Real name: Hunter Mason. A hulking, tattooed gangster who serves as the leader of the Purple Dragons street gang.
- Animorphism: To a mutant turtle, in Turtles Forever.
- Arch-Enemy: To Casey in most continuities. He killed Casey's father.
- Authority Equals Asskicking: One of the two constants about him is that he always is the leader of the Purple Dragons, and the strongest in the gang.
- Badass Longcoat: At one point.
- Badass Normal: A regular human with no mutation whatsoever, but still capable of giving a hard time to the Turtles of his own.
- Berserk Button: Unless you want Hun to rudely tell you to leave him alone, do not persist with him that he placed an order. The result? Hun: (Growling) "GO AWAY! WE! PLACED! NO! ORDER!"
- The Brute: He is not stupid, but still, he is the Shredder's biggest and strongest enforcer.
- Canon Immigrant: He was originally created for the 4Kids show, but got popular enough to be adapted back into the comics, and later introduced (though considerably different) in the Nickeldeon cartoon.
- Catchphrase: "Oh, crud"
- The Dragon: To Shredder, though he eventually becoming Co Dragon alongside Karai.
- Dragon Ascendant: When Hun finds out Oroku Saki is actually an alien named Ch'rell he leaves The Foot Clan, and does a complete makeover of The Purple Dragons, transforming them from simple street thugs into a veritable army that pulls off some very high risk & high reward theft jobs from Multinational Corporations & even the military.
- However come Turtles Forever after he gets mutated into Slash he willingly decides to get Demoted to Dragon & serve Ch'rell once again.
- Empowered Badass Normal: In Turtles Forever.
- Fingerless Gloves
- Guilty Pleasures: In-show variation with Hun. Running the Purple Dragons is one thing, but who would've thought he plays the same MMORPG that Mikey does? Not to mention he, unknowingly, met the Turtles in it and helped them get Splinter's data bits.
- Karmic Transformation: In Turtles Forever, he ends up mutated into a Slash-esque Turtle after being in contact with both 2003 Raph and the old cartoon's Mutagen. To say he doesn't take it well would be quite an understatement.
- Large and in Charge
- Lightning Bruiser: Don't let his size fool you, Hun is astonishingly fast—more than fast enough to be a match for the turtles.
- Most Gamers Are Male: Size doesn't seem to matter for him.
- Punctuated! For! Emphasis!: Is it any surprise that Hun has at least one moment of this? Hun: "Arrrrrgh! Go away! WE! PLACED! NO! ORDER!"
- Scars Are Forever: Hun sports a trio of matching scars on his face, courtesy of a pre-mutation Splinter.
- Tattooed Crook: Hhe sports twin tattoos of the Foot and Purple Dragon symbols, removing the former after he leaves the organization for good.
- Took a Level in Badass: In Season 4, Hun transforms the Purple Dragons from a petty street gang working for the Foot into a far more sophisticated organization operating on its own.
- Would Hit a Girl: He was willing to hit April, hoping that losing her would cause the turtles to lose their fighting spirit. In City At War, Part 3, Hun smacks Karai around with a support beam.
Superheroes and supervillains
One of Michelangelo's superhero idols and the leader of the modern-day Justice Force.
- Captain Ersatz: Of Superman.
- Chest Insignia: A stylized bird—probably.
- Flying Brick
- Super Toughness
- Xray Vision
A hydrokinetic super-hero from Japan who joins the Justice Force in season 3.
An psychokinetic super-hero from India who joins the Justice Force in season 3.
A sentient nanomachine colony who escapes its creators and causes trouble.
- Anti-Villain: It either has the mindset of a child or is being controlled by outside forces; either way, it is rarely entirely responsible for its actions.
- Crush. Kill. Destroy!
- Heel–Face Turn: In season 5.
- I Just Want to Be Loved: It views itself as a child who wants to be loved by its "mother", the doctor who created it, and its "father", Harry the con artist.
- Instant A.I., Just Add Water: For unexplained reason, the nano-machine colony started personifying, to its creator's chagrin.
- Nano Machines
- Obliviously Evil
- Tragic Villain: Sure, it caused destruction almost everywhere it went, but its supposed death scenes are rather disheartening.
Green Lantern if Green Lantern got his powers from a cape.
- Captain Ersatz: Of Green Lantern, specifically Hal Jordan.
- Clothes Make the Superman
- Lantern Jaw of Justice
Turtle Titan II
A man who takes on Michelangelo's old super-heroic identity.
- Animal-Themed Superbeing
- Identical Grandson: Of Silver Sentry.
- Jetpack: How he flies.
- Legacy Character: A twofer, continuing the legacies of both Michelangelo and Silver Sentry.
Silver Sentry's arch-enemy, who uses his engineering prowess to commit super-crime.
- Dr. Genericius
- Hypno Trinkets: The mind-control bugs he uses in his debut activity.
- Mad Scientist
- Morally Ambiguous Doctorate
- The Bus Came Back: He made just one appearance in the first season during Michelangelo's teamup episode with Silver Sentry and remains absent for the remainder of the series(aside from appearing in a story told by Michelangelo during Fast Forward) until the seventh and final season where he makes one more official appearance.
The Battle Nexus
The Ultimate Ninja
A warrior who comes to Earth to challenge Leo to mortal combat.
- Antagonistic Offspring: The son of the Daimyo.
- Artificial Limbs: Specifically, his left hand.
- Everyone Calls Him "Barkeep": This guy is never identified by name, except as Drako when he merges with him in the third season.
- Fusion Dance: With Drako during the third season.
- Meaningful Rename: “The Ultimate Ninja” is what he calls himself after he believe he's defeated Leonardo.
- Sore Loser: Attempts to kill Leonardo after being officially defeated.
- Taken for Granite / Literally Shattered Lives: This is how he initially dies after "Same As It Never Was" and "The Real World", but he's brought back to life as a child; Drako stays dead.
- Party Scattering: He and Drako as Ultimate Drako are the ones responsible for sending Donatello to the infamous "Same As It Never Was" universe with the Shredder ruling all, while Leo winds with with Usagi Yojimbo.
- Raise Him Right This Time: After he is killed Lord Simultaneous revives him as a child. It's implied the Daimyo will do this.
- The Unfavorite
- Walking Armory: Swords, Wolverine Claws, chain and sickle, shuriken, blinding dust—the works.
Ruler of the Battle Nexus and The Ultimate Ninja's father.
- Everyone Calls Him "Barkeep": His true name is never identified.
- The Good King
- Long Lived
- Old Master
- Sanity Slippage: In the third season, it is clear he has not taken the loss of his son very well.
A Battle Nexus Championship contestant who was defeated by Splinter years ago.
- A Dog Named "Dog": He's a red dragon named Drako.
- Fusion Dance: Merges with the Daimyo's son in Season 3.
- Killed Off for Real: Petrified and destroyed two episodes after scattering the clan.
- Party Scattering: He and the Ultimate Ninja as Ultimate Drako are the ones responsible for sending Donatello to the infamous "Same As It Never Was" universe with the Shredder ruling all, while Leo winds with with Usagi Yojimbo.
- Sore Loser: Attempts to have Splinter killed after having lost the Battle Nexus Tournament.
- Taken for Granite / Literally Shattered Lives: This is how Drako finally meets his end after he scatters the Hamato Clan (one of whom, Donatello, gets to witness what will happen should main Big Bad Ch'rell/The Shredder prevail) and is confronted for it. The Ultimate Ninja is brought back to life, but Drako isn't.
A Battle Nexus Championship contestant with an animus towards Michelangelo.
- Ambiguously Evil: While he eventually tries to kill Michelangelo for purely selfish reasons, he also formed part of Traximus' rebel army, which makes it rather hard to get a sense of him.
- Sdrawkcab Name: The character is meant to be a homage to The Hulk.
- Sore Loser: Although he has a point about only losing on a technicality, it eventually becomes clear that he doesn't really give a damn about the Battle Nexus Championship or its rules.
- Super Mode: Inverted, more or less, as he spends way more time in his hulked-out form than he does in his smaller state.
The Ninja Tribunal Arc
The Ancient One
Hamato Yoshi's adoptive parent and, for a time, Leonardo's sensei.
- Back for the Finale: He's one of the guests at Casey and April's wedding and takes part in the ensuing battle against the Cyber Shredder.
- Big Good: Shares the role with Splinter in the fifth season after the apparent deaths of the Tribunal.
- Gass Hole: Early on, he teaches Leo a lesson on how he can't win all his battles by getting him pit against some near invincible warriors. How did the Ancient One put through Leonardo through this lesson? By farting and alerting said warriors to their presence.
- My Greatest Failure: He blames himself for not doing anything about the darkness in Mashimi's heart before his murder of Tang Shen.
- No Name Given
- Obfuscating Stupidity: Once Leonardo learns of his true nature, he drops the crazy mentor facade, though he remains fairly whimsical until the fifth season.
- Old Master
- Reasonable Authority Figure: Leonardo and Michelangelo even wish they could be studying under him over the rough Tribunal.
- Trickster Mentor: At first.
The Ninja Tribunal
A quartet of long-lived ninja masters who have made it their lives mission to stop the Demon Shredder. Their names are Kon, Juto, Chikara, and Hisomi.
- Amazonian Beauty : Chikara. Adam certainly thinks so.
- Big Good
- The Chessmasters
- Color-Coded Characters: Hisomi is yellow/gold. Chikara is green. Juto is blue. Kon is white.
- Disney Death: They are only revealed to have survived in the ending of the season finale.
- Good Is Not Nice
- Meaningful Name: Chikara's name is the Japanese word for "Power". Her specialty is physical strength.
- Physical Gods
- The Omniscient Council of Vagueness: Initially, anyway.
- The Smurfette Principle: Chikara is the only female member.
- Sacrificial Lions
- What the Hell, Hero?: This is how Splinter (and the audience) react when the Ninja Tribunal refused to do anything about the Utrom Shredder, even allowing him to kill Master Yoshi. Justified when it's revealed that without Yoshi's death, Splinter and the turtles wouldn't have been mutated, something Don lampshaded 3 seasons ago in the Clip Show episode.
Four martial artists who were kidnapped along with the turtles to serve as the Ninja Tribunal's apprentices. Their names are Faraji Ngala, Joi Reynard, Adam McKay, and Tora Yoshida
- Back for the Finale: They're guests at Casey and April's wedding, and fight against the Cyber Shredder.
- Overshadowed by Awesome:
- Sacrificial Lions: They eventually come back, but their “deaths” serve this purpose.
- Satellite Characters: Each acolyte establishes a rapport with a particular turtle, whom they revolve around—Faraji befriends Leo, Joi bonds with Raph, etc.
The Shredder's Heralds / Foot Mystics
The Demon's Shredders, who had been forced to serve the Utrom Shredder until they engineered their freedom.
- Ascended Extra: They were one-off villains for the penultimate arc of the first season, and voiceless. They return early in the fourth season, and nearly mentally break the Turtles, discover the location of their lair, and facilitate a plot that leads to the return of the Tengu Shredder, becoming the BigBad's for the first half of the fifth season before returning to their role as his Dragons.
- Big Bad: For the first half of the fifth season.
- Because You Were Nice to Me: A non-romantic example; though they deem Ch'Rell an "Utrom abomination", they appreciated his large amount of respect for their powers when they served him, in comparison to his daughter, who cares less what they think.
- Elemental Powers
- The Dragons: For the demon Shredder
- Revenge Before Reason: Despite their loyalty to the demon Shredder, they are obsessed with getting revenge on Karai. They question him why he isn't concern to punish Karai for using his name, he tells them he's cares more about ruling the world. Though they don't wish to deter their master with his plans, this does not sit well with them. They also fume over the Shredder's lack of action when the Turtles and their allies attack their fortress.
- Voluntary Shapeshifting
- You Have Outlived Your Usefulness: Demon Shredder let them get killed.
Casey and April's great-grandson and heir to both O'Neil Tech and the Jones fortune.
- Ascended Fanboy: Grew up reading April and Casey's journals about the turtles. The entire Fast Forward season started because he made a device to watch their adventures through time and accidentally yanked them into the future.
- The Cameo: He briefly appears in the finale, watching the wedding of his great-grandparents through the Time Window.
- Conveniently an Orphan: Both of his parents are dead and his only relative is his Obviously Evil Uncle.
- Gadgeteer Genius: Invented Time Travel. By accident.
- Lonely Rich Kid: The only people in his life before the Turtles and Splinter came to the future were his robot butler and Evil Uncle, so he's thrilled to have his personal heroes crash at his penthouse.
- Non-Idle Rich: To Serling's dismay.
- Significant Green-Eyed Redhead: Well, obviously since he's April and Casey's future great-grandson.
- Tagalong Kid
- Teen Genius
Cody's robotic caretaker, who only barely tolerates the turtles.
- Arm Cannon: As Turtle X Mark II
- Backto Back Badasses: With Splinter in "Bad Blood".
- Badass Boast: During the Darkest Hour of Dunn's attack in "Turtle X-tinction."Serling: It will be a cold day in Hades before I allow you [Cody] to come to harm!
- Battle Butler: He was no slouch in fighting beforehand, but becomes the new Turtle X armor late into the sixth season.
- Berserk Button: Messing with Cody. Dun learned this the hard way.
- Disney Death: See Heroic Sacrifice.
- Fish Out of Temporal Water: In the seventh season. He ends up being sent back into the 21st century by Viral, and doesn't entirely enjoy the experience, though Word of God says he ended up thinking his stay was worth it when he got to witness the wedding of Casey and April.
- Heroic Sacrifice: Pulls one in "Turtle X-Tinction".
- Mini-Mecha: As Turtle X Mark II
- Robot Butler
- Transforming Mecha: As Turtle X Mark II
- True Companions: He may dislike the Turtles, but he gets along very well with Master Splinter, and later Donatello.
- What Happened to the Mouse?: At the end of the series, he's still in the present day, but is nowhere to be seen in Turtles Forever.
Cody's uncle and legal guardian, he uses his position as the C.E.O. of O'Neil Tech to facilitate various shady dealings.
- Berserk Button: Cody says he hates being called "fatty."
- Big Bad: Shares the role with Sh'Okanabo for the sixth season.
- Canon Immigrant: He is introduced into the IDW comics, a whopping decade after his debut in Fast Forward.
- Corrupt Corporate Executive
- Evil Uncle
- Fat Bastard: He's gigantic.
- High-Class Glass
- Illegal Guardian
- Knight of Cerebus: By virtue of being Cody's Evil Uncle, he has a far more personal effect on the heroes when he finally does get outed and nearly kills Cody and Serling.
- Manipulative Bastard
- Parental Substitute: Is Cody's main figure of authority.
- Spell My Name with an "S"
- Took a Level in Jerkass: One of Serling's home movies was of him affably ruffling a younger Cody's hair, implying at some point in the past he actually was a good uncle to him.
- Villain with Good Publicity: He starts out this way at the beginning of his arc.
- What Happened to the Mouse?: Thanks to the Aborted Arc of the Fast Forward season, his final fate was never revealed.
- You Monster!: Splinter is repulsed by him.Splinter: I have met many monsters in my time, Dunn, but it takes a special breed to direct such bile and hatred against a child!
An alien invader who has determined that Earth is the ideal planet for him to spread his gene-seed.
- Arc Villain: Of Fast Forward.
- Back for the Finale: After his own Time Window goes haywire, he disappears until the penultimate (though for all effects the final) episode of Fast Forward.
- Big Bad Ensemble: With Darius Dun.
- Big Bad Duumvirate: He later forms one with Darius Dun for the first half of Fast Forward.
- Expy: He shows more than a few similarities to Lord Dregg.
- Karma Houdini: He tricked Torbin Zixx into smuggling a bomb onto a spacecraft and while Zixx did rat him out to the turtles, who in turn reported it to Bishop, Sh'Okanabo never got in trouble for almost hurting many innocent beings.
- Knight of Cerebus: Episodes that feature him as the main antagonist are far more serious with larger ramifications.
- Killed Off for Real
- Light Is Good/Dark Is Evil: He looks dark and works in the shadows, is never seen walking around in daylight, if weak enough, sunlight can hurt him and he was killed by a solar grenade.
- Spikes of Villainy
- The Virus: Anyone infected with his gene seeds becomes a Kanabo drone subservient to him.
- Voluntary Shapeshifting
Constable Aloysius Biggles
A robot who serves as an officer of the New New York Peacekeepers and who keeps running into the turtles.
- British Copper: In intent if not in reality.
- Butt Monkey: To the point that the main gag of a preview of an episode revolved around his really long fall from a skyscraper, and Michelangelo finally admits at the end of the promo that someone should probably save him. Funnily enough, in the episode proper this is not played for laughs.
- Catchphrase: “'Allo 'Allo 'Allo. Wot's all this then?”
- Inspector Javert: Occasionally, most notably in “Playtime's Over”
- Ridiculously Human Robot: Despite being presumably programmed for the job, he rather dislikes the paperwork it involves.
An A.I. who serves under Sh'Okanabo.
- Cyber Cyclops: In her corporeal form, anyway.
- The Dragon: Was Sh'Okanabo's lieutenant during his arc.
- Digitized Hacker
- Fish Out of Temporal Water: She gets stuck in the twenty-first century at the beginning of season 7.
- Shapeshifter Weapon: Her corporeal form is based on a shape-shifting training bot, whose limbs can turn into things like chainsaws.
An O'Neil Tech intern and friend of Cody Jones.
- A Day in the Limelight: "Enter the Jammerhead"'s main subplot revolves around her and her family coming to visit.
- Adorkable: When she's flirting with Cody and fawning over him.
- Blue-Skinned Space Babe: Complete with a True Blue Femininity appearance.
- Fat Girl: Played for Laughs when her mother sees her for the first time in a while and asks if she's put on weight, when Starlee is slender.
- Full Name Ultimatum: Pulls one on Cody Augustus Jones when pretending to be mad over him ditching her in the mall.
- Interspecies Romance: Clearly wants this with Cody as "Playtime's Over" revealed, and soon enough it seems they are dating.
- Nice Girl: A sweet girl who's loyal to Cody and the gang.
- Rollerblade Good
- Rubber-Forehead Alien: Pointy ears, blue skin, and large eyes differentiate her from standard humans.
- Ship Tease: In "Playtime's Over", she manages to swindle Cody into a date and is happily attached to his arm, batting her eyes and giggling.
- Single Woman Seeks Good Man: She falls for Cody harder when she sees him run off to save the Turtles.
- Teen Genius
A cyborg who runs the Street Phantoms, a New York gang.
- Compressed Hair: His hair is completely obscured by his hood despite the fact that it's several feet high.
- Intangible Man: Like all members of the Street Phantoms, thanks to their phasing tachnology.
- Slasher Smile
- Smarter Than You Look
The Inuwashi Gunjin
A quartet of winged humanoids who serve as Darius Dun's reluctant enforcers.
- Anti-Villains: They work for Darius Dun only because they have been implanted with electronic machines that Dun uses to torture and contain them. They kidnap Cody and threaten to kill him if Dun (who needs Cody alive) won't free them. They note the turtles' honor for repeatedly saving Cody who's little help to them (at the time). They finally decide to follow the turtles' example of honorability and give them time to escape from drowning.
- Forced into Evil
- Heel–Face Turn: They all pull one once they are finally freed from Dun's control.
- Last of Their Kind
- Proud Warrior Race Guys: Their race was once the most feared force of earth and sky.
- Winged Humanoids
- Worthy Opponents: As they witness the turtles saving multiple times Cody who's not much of a help in a fight, they remark that to be truly honorable.
The Dark Turtles
Created by Sh'Okanabo from the turtles' genetic material, these four mutant turtles serve Darius Dun. They are all voiced by the same actors for the original turtles.
- Big Brother Instinct: Kind of a grey area. Towards the end of "DNA Is Thicker Than Blood", Dark Leo divides up the meat among his brothers. This action is so unexpected that it sparks confusion among them.
- Color-Coded Characters: The color of each turtles' skin more or less corresponds to their counterparts' bandanna colors.
- Dark Is Evil: At first. They were more than eager to try destroying their original counterparts.
- Dark Is Not Evil: They have the capacity to be better if they were given the chance.
- Dumb Muscle: Dark Raph. He was so stupid that he couldn't pick up Mikey's sarcasm.
- Evil Twins
- Forced into Evil: While it doesn't occur in the same way as with their predecessors the Gunjin, the episode “D.N.A. is Thicker Than Water implies that they have the capacity to be better turtles if it weren't for the fact that they are forced to work for Dun.
- Geek Physiques: Dark Don is the tallest and skinniest of the quartet.
- I'm a Humanitarian:Dark Raph: Let's crack your shell open and see if there's a yummy cream filling inside!
- Laughing Mad: All of them, primarily Dark Mikey.
- Oddball Doppelgangers
- Off with His Head!: In their first 2 appearances, Dark Leo threatened to cut off someone's head.Dark Leo: *holding his sword next to Cody's neck* No sudden moves, or your friend here loses his head.Leonardo: How long have you been working for Dun?Dark Leo: Details, details, you should be paying attention to more immediate matters, like keeping your head on!
- Psycho Rangers
- Reptiles Are Abhorrent
- Slasher Smile / Psychotic Smirk: They at least show off one.
A famed mercenary who has several run-ins with the turtles.
- Advertised Extra: He appears in the opening titles, despite his sporadic appearances in the series.
- Combat Pragmatist
- Con Man
- Even Evil Has Standards: Deliver/smuggle an illegal package for an alien? Sure. Said package turns out to be a bomb that could've potentially hurt many innocent humans and aliens? Yeah, big mistake.
- Heroic Sacrifice: Volunteers to make one in the final episode of Fast Forward to save Earth from a dark matter asteroid. It's actually his ship, which he escaped to with a device that had been jury-rigged to destroy the asteroid.
- Wild Card / Chaotic Neutral
A pro-wrestler turned criminal who sports three heads, each with its own personality.
A government agent who will do absolutely anything to protect Earth from aliens invasion. Head of the Earth Protection Force.
- 0% Approval Rating: In modern times, the Turtles, Splinter, Leatherhead, and even the Foot Clan thoroughly despise him and Raphael even went on record as to say he hated Bishop more than his Arch-Enemy Hun. Even an important political ally to Bishop like the President of the United States itself doesn't seem to like Bishop all that much and has chewed Bishop out for constantly acting on his own. And even Baxter Stockman, the closest thing Bishop has to a friend in the show, quickly grew disillusioned with working under Bishop, based on how Bishop has constantly stalled him from working on a new human body or brought him back from the dead even though Stockman wanted more than anything to rest in peace.
- Alien Blood: Despite being human.
- Ambiguously Human: He was definitely human at some point, but after a certain event some 200 years ago, it's no longer clear what he is.
- Anti-Villain: He genuinely tries to protect humanity from potential alien invaders. The problem is, he is sadistic, amoral, suffers a huge case of Fantastic Racism against aliens and mutants as a whole, and conducts horrible experiments o reach his goals.
- The Atoner: In Fast Forward.
- Badass Longcoat: Part of his signature look.
- Back for the Finale: After being absent for the entirety of the final season, he makes a cameo watching April and Casey's wedding with approval.
- Benevolent Boss: He can be stern or angry toward Stockman, but for the most part, he shows genuine concern for his condition (if just because he still needs Baxter's knowledge) and, unlike the Shredder, never threaten to kill or mutilate him for his failure.
- Big Bad Ensemble: He's the most prominent antagonist in the third season not aligned with the Foot. After the final defeat of Ch'Rell, in the fourth season, he forms an ensemble with Hun and Karai, with Stockman as his Dragon.
- Canon Immigrant: A character who talks while off-panel in one issue of the Mirage Comics has been confirmed by Word of God to be him.
- Clone Degeneration: He survived so long by regularly cloning himself in a new body that ends up degenerating after a while, forcing him to do it over and over again.
- Combat Pragmatist: He ends up using his own tie to fight the Turtles, Karai and Hun and still continues to kick ass.
- Dark Is Evil: As a villain, his suit is black.
- Enemy Mine: Twice:
- When the mutagen he used to create a fake alien invasion ends up unleashing mutants on New York, he teams up with the Turtles and Leatherhead to end it.
- In the fifth season, he is amongst the many villains who join force with the Turtles to stop Tengu Shredder.
- The Extremist Was Right: In "Aliens Among Us".
- Four Eyes, Zero Soul: He's never seen without a pair of sunglasses, and he's a bad guy.
- Freudian Excuse: In the 1800s, Bishop was a soldier in the Civil War who was abducted by aliens, being experimented on and genetically altered, turning him into the xenophobic Well-Intentioned Extremist he is in modern times who's willing to cross any moral boundary in order to keep Earth safe from alien incursions. Given his past, it's quite understandable why he became the man he is today, though in no way does this justify all the lives he's ruined and the people he's hurt.
- Heel–Face Turn: In Fast Forward.
- Heel Realization: In Fast Forward, he became a better person after an alien he was experimenting on saved his life, altering his view of extraterrestrials considerably.
- He Who Fights Monsters: He was experimented on and never wants that fate to befall another human, but himself has experimented on aliens, regardless of their innocence.
- Karma Houdini: Though he at least learnt from his mistakes and tries to atone for what he did.
- Light Is Good: In Fast Forward where he's become good, his suit is white.
- One-Man Army: He can hold his own against all four of the turtles, AND Karai and Hun all at the same time. He's also seen effortlessly fending off the Foot Elite in Exodus.
- Promotion to Opening Titles: From the fourth season to the sixth season.
- Really 700 Years Old: He's somewhere around 220.
- Sinister Shades: In his battle outfit, and in Fast Forward.
- Supporting Leader: When the Turtles and Karai are fighting the Demon Shredder, Bishop takes command of the Purple Dragons AND the Justice Force along with his own men.
- Unwitting Pawn: In "Good Genes", he is promised an alien artifact of great power by an unknown entity, and has the Turtles retrieve it for him. When he gets it, he ends up destroying it, which frees the Foot Mystics from Karai's control, leading to the return of the Demon Shredder.
- Villain with Good Publicity: A downplayed example. He's a very secretive government agent and very few people know of his actual existence. However, he has the backing of the United States government and by the fourth season, the unconditional support of the President himself, which makes him arguably as big of a threat to the Turtles as the Foot Clan, if not moreso. He becomes yet another downplayed example by the time of Fast Forward because by that time, everyone knows of his existence and he's extremely well liked by almost everybody on Earth... but by that time, he's pulled a Heel–Face Turn and is no longer an actual villain.
- Well-Intentioned Extremist: In the present.
Yukio MashimiHamato Yoshi's friend and surrogate brother.
- Expy: For Oroku Nagi, who was Adapted Out, being the one to compete with Hamato Yoshi for Tang Shen's feelings.
- Green-Eyed Monster: Eventually, Tang Shen not requiting his feelings and Hamato Yoshi going onto a promising ordeal resulted in Mashimi murdering Tang Shen, and betraying Yoshi to the Foot Clan.
- My God, What Have I Done?: Before he dies, he asks Yoshi to forgive him for all the horrible atrocities he caused.
- Small Role, Big Impact: Without him betraying the Utroms and Yoshi to the Foot Clan and his murder of Tang Shen, Splinter and the Turtles as they are may well not have existed.