Characters / The Adventures of Jimmy Neutron, Boy Genius

For characters from the Planet Sheen spin-off, see here.

Main Characters

Jimmy Neutron

He may be small, but he has a big brain!

Voiced by: Debi Derryberry

Full Name: James Isaac Neutron

The main protagonist and titular boy genius. He is a boy with a stunning IQ of 210 and a love for science. From Hypercubes to Hypnorays, Jimmy can whip up the most amazing inventions. However, things have a way of going awry, and more often than not, Jimmy has to save the day from himself. But with friends, family, and a secret lab, there's no problem this boy genius can't handle. Right?

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• Aesop Amnesia: At least half of the episode plots wouldn't happen if Jimmy would remember how often his inventions backfired or that using his genius for his own ends has its consequences.
  Cindy: Jimmy, haven't you learned from the Yolkian incident not to talk to intergalactic strangers?
• Affectionate Nickname: Hugh calls him "Jimbo".
• All of the Other Reindeer: Jimmy's brains and brilliance (along with him endangering the town) make him unpopular with the other kids and as a result, he's made fun of and bullied by them.
• Anime Hair: Lampshaded consistently. It's been compared to a gum massager, soft-serve ice cream, fudge dip, and still other more ridiculous things. He's also been called "Fudgehead" by Timmy and Cosmo.
• Anti-Hero: Jimmy is a complex character, often prone to arrogance and mischief, although the good side of his personality usually outweighs the bad one.
• Arbitrary Skepticism: Best shown in the Jimmy-Timmy Power Hour trilogy and Nicktoons Unite!. Despite living in a world where space aliens and alternate dimensions exist, Jimmy refuses to believe in magic and is convinced that the fairies and associated creatures in the Fairly OddParents universe are merely highly advanced computer programs.
• Arch-Enemy: He has made himself a lot of enemies but probably the three biggest examples are King Goobot, Finbarr Calamitous and Eustace Strych.
• Badass Adorable: A dorky young Child Prodigy who's saved the world on numerous occasions.
• Big "NO!": Whenever Jimmy comes to any shocking realization, you can bet the whole of Retroville will know about it instantaneously.
  • In "The Tomorrow Boys", after learning he gets married to Cindy. In a bit of Leaning on the Fourth Wall, the scream cuts to a commercial. When the show comes back on, Sheen and Carl comment that he had been screaming for four minutes straight.
  • Another Cindy-related moment is when he finally succeeded in asking Cindy on a date, only then he realized what he'd done
  • It even happens with a similar situation where in Jimmy Neutron vs. Jimmy Negatron, where Cindy falls in love with Negatron.
• Big, Thin, Short Trio: The Short to Carl's Big and Sheen's Thin, although he compensates for his short stature with a combination of both his big skull and his tall, swirly hairdo.
• Black Sheep: In "Clash of the Cousins," most of the Neutron extended family views him as such, correctly pointing out that, while Jimmy may have saved the day quite often, more often than not, it was one of his inventions that caused the problem in the first place. Subverted by the end when he saves them all and they appreciate him more, especially since he saves them from the new Neutron Black Sheep, Jimmy's cousin Eddie, who is just as intelligent, but villainous (and a baby).
• Brainy Brunette: Brown hair? Check. Incredibly intelligent? Check.
• Brilliant, but Lazy: Why do something as simple as neatly put away your piles of pants when you can implant chips in them that do it for you? Carl and Sheen call him out on this, though.
• Break the Cutie: He becomes a victim of this whenever something really bad happens to someone he deeply cares about. Especially Goddard. This also happens when his insecurities are shown. In "The N-Men", Jimmy spends pretty much the entire episode being bullied, ignored, and insulted by his so-called "friends". He becomes so fed up, that he turns into a Hulk-like creature and terrorizes the town for revenge.
• Breakout Character: During the time of the film's release and the early run of the series, Jimmy became Nickelodeon's official mascot.
• Bungling Inventor: While he's undoubtedly a genius, the plots of most episodes are kicked off when his inventions go haywire.
• Butt-Monkey: His inventions usually cause trouble. And when it doesn't come to his inventions, he's picked on by those left and right.
• Cassandra Truth: In the episode "The Eggpire Strikes Back", no one believes Jimmy when he says that the Yolkians, the villains from the film, are still just as evil as ever, until the Yolkians trap them in the park and sic Poultra on them.
• Catchphrase: Originally "Gotta blast!", "Think, think, THINK!", and "Brain blast!". The show eased off on these as it went on, eventually getting rid of them entirely. (One exception is "And now, my latest invention, the (insert plot-related-device here!)", which stayed for most of the series' run.)
• Chick Magnet: He gets a lot of attention from girls.
• Child Prodigy: A boy genius who has an IQ of 210.
• Characterization Marches On: Jimmy is eventually transformed from a shy Innocent Prodigy with an everlasting passion for having fun to a more ill-mannered and insufferable boy genius with an everlasting greed for superiority.
• Cheaters Never Prosper: Jimmy sometimes uses his inventions to cheat in competitions, and it ultimately backfires on him.
  • In "Maximum Hugh", he and Hugh are disqualified from the Picnic Games for cheating, though he was the one who decided to admit it and turned down the trophy. In a hilarious example, it turns out that almost everyone cheated in the games in the first place (Cindy's case was apparently unintentional on her part)... except for the Wheezers, who won by default.
  • Jimmy finds this out the hard way in "The Retroville 9" when he and his friends lose the baseball championships without scoring a single point. Then, Tremendous Jackson offers this hilarious line:
  Tremendous Jackson: Somewhere in the Rytridian Galaxy, Ultra Lord weeps.
  • In "Jimmy for President" has an... unusual example. He is disqualified due to "operating a zeppelin onto school premises" (compared to Cindy and Sheen, who relied on more traditional means, as well as bribery and blackmail).
• Crazy-Prepared: His watch, whose powers depend mainly on the plot. Can include lasers, freeze rays, magno-rays, GPS, tracking devices... you name it, there's probably a gadget for it tucked away in there.
• Crippling Overspecialization: He's extremely intelligent but sees anything else as fairly beneath him, leaving him useless in a ton of non-science-related activities, including things so simple as selling candy door-to-door because instead of trying to sell the candy, he's giving chemistry lessons, and is then confused on why it's not working.
• Deadpan Snarker: In Season 3's "Carl Wheezer Boy Genius".
  Jimmy: *science babble about a spider*
  Sheen: Fascinating! Can you make it do the hokey pokey?
  Jimmy: Sheen, go home.
• Ditzy Genius: He's undeniably smart, but has a lack of common sense and can be arrogant.
• Don't You Dare Pity Me!: Subverted. Describing himself as a "genius", Jimmy often brushes off other characters every time they try to point out a problem in his plans and/or his own flaws, thinking they're just trying to feel sorry for him.
• Drunk with Power: In "Hall Monster". He becomes hall monitor and, when the principal gives him advice and is told that Albert Einstein was a hall monitor as well, becomes determined to be one of the best. Unfortunately, when combined with his weirdly heavy-handed law enforcement inventions, it leads to a power trip that causes him to run the school like a prison.
• Early Installment Character-Design Difference:
  • In the original Runaway Rocketboy short, Jimmy wore a red and white striped shirt. In the movie, this was swapped out for a red shirt with an atom on it.
  • In the show, Jimmy swapped out the shorts and brown loafers he wore in the movie for jeans and sneakers.
• Endearingly Dorky: This was especially evident in the shorts, movie, and Season 1 where he was a lot more shy, clumsy, awkward, and naive. This is why he gets a lot of attention from girls in-universe.
• Establishing Character Moment: Jimmy has several early in the movie.
  • He refers to the fighter jets as "nice antiques" when they catch up to his homemade rocket in the first scene.
  • He shares one with Cindy by responding to her show-and-tell about Girl Dinosaurs being superior to Boy Dinosaurs by referring to a sub-field of the scientific community, which she responds to in kind by describing the findings Jimmy used against her as inconclusive.
  • Balancing out his impulsiveness and arrogance, Jimmy is also established to have a large streak of kindness where Carl is concerned, genuinely complimenting the latter on his childish drawing of a frog and making no fuss over his photorealistic drafting of Goddard's second fly-cycle prototype.
• "Eureka!" Moment: Usually when he has to really think of the solution, followed by "Brain Blast!"
• Fatal Flaw: Jimmy's greatest flaws are a combo of Pride, Sloth and his lack of common sense; in fact, many of the conflicts in the show are born out of this.
• The Friend Nobody Likes: Most of Jimmy's classmates don't like him that much due to his massive smarts which leaves him ostracized. This is especially evident in episodes like "Lights Camera Danger", "Men at Work", "Jimmy Goes to College", and "Normal Boy".
• Future Loser: In the 'Bad Future' of "The Tomorrow Boys", Jimmy is a slack-jawed loser, wanted by the evil dictator Libby, with a five-o'clock shadow and Cindy as a wife. Naturally, Jimmy is less than impressed.
• Gadgeteer Genius: He's only a kid, but he has already surpassed any known scientist in capability. Each episode focuses on one of his inventions although his inventions usually fall prey to "Flowers for Algernon" Syndrome.
• Get Back to the Future: Jimmy's dad screwed up with one of his inventions, leaving him, Carl and Sheen in the past.
• Give Geeks a Chance: Despite being relatively unpopular, he has caught the eyes of girls due to his smarts and heroic nature.
• He Cleans Up Nicely:
  • When Jimmy shows up in a tux for Jet Fusion's wedding to Beautiful Gorgeous in "My Big Fat Spy Wedding", Cindy promptly gets little hearts in her eyes.
  Cindy: So Neutron's the best man? Yeah, more like the best NERD! I bet he'll look like a total... (Jimmy shows up outside the church in a tux. Cue fade to pink background, eye-hearts and hair patting) ...HUNKMUFFIN.
  • During Love Potion #976-J, when Jimmy cleans up for his date with Cindy. Said almost word-for-word by Cindy.
• Height Angst: He's shorter that the main casts (and Retroville kids his age in general), and he loses his temper when someone mentions or ridicule his short stature.
• "Hell, Yes!" Moment: Often. Especially when he's given up all hope...and then his friends forgive him for being arrogant/apologize for being stupid/come back to save him.
• Hidden Depths: Some episodes imply or outright state that Jimmy may actually be more insecure of himself and is not as conceited or confident as he makes himself out to be.
• HULK MASH!-Up: In "The N-Men", the kids all get various superpowers that parody real comic book heroes. Jimmy turns orange like The Thing and becomes a parody of both the Hulk and his alter ego Bruce Banner; while normally mild-mannered and highly intelligent like Bruce, his true powers awaken when he gets mocked and becomes a towering, infuriated beast of a man trying to destroy everything in this path.
• Hulk Out: His actual superpower in "The N-Men". He becomes the Hulk with elements of The Thing of the Fantastic Four, granting him inhuman strength, agility, and a Healing Factor.
• Ignored Expert: Whenever Jimmy tries to use his incredible scientific mind to solve a problem that wasn't directly his fault or he could fix easily if left to his own devices (the Yokians returning, the Mysterious Space-Rock, the Niblonians, etc.), expect human-error, irrational behavior or learned distrust from everyone else to get in Jimmy's way until the problem gets so out of hand that they can't ignore it.
• I'm Your Worst Nightmare: His quote when first introducing himself and the others as N-Men.
  Jimmy: Who am I? I'm your worst nightmare.
  —later...—
  Cindy: By the way Neutron, who said you can issue a corny battle cry and where do you come up with N-Men?
• Innocent Blue Eyes: Has dark blue eyes which represent his heroism and brainy nature.
• Innocent Prodigy: He's a genius when it comes to science and technology, but he's also extremely naive and childish, even for his age. A lot of plots are set in motion because his ability to invent vastly outstrips his ability to understand the consequences.
• Insufferable Genius: He does try to be modest (even creating a device to measure arrogance), but he's legitimately so much smarter than a lot of people that it's difficult for him. This escalates when Cindy is around (who used to be the smart girl).
• Intelligence Equals Isolation: Downplayed. Jimmy's intelligence isolates him, he often sets the (horrible) events of the plot in motion, causing him to be isolated, sometimes the characters realize they need his intellect and/or like him more than they let on, and sometimes he's just an insufferable genius. That said, unlike a lot of examples of this trope, he has a consistent, mutually beneficial friend circle and can actually interact with people without freezing up.
• It's All My Fault: For all his Insufferable Genius and Disproportionate Retribution moments, not once was there ever a single moment where he would refuse to take responsibility for his actions or even flat-out try to downplay them whenever his inventions would cause some sort of catastrophe at worst, and more often than not he is willing to clean up the mess he made himself.
• Jerkass Has a Point: As snobby as he can be, Jimmy's claims on certain things can be legitimate.
• Jerk with a Heart of Gold: Jimmy tends to be arrogant, condescending, and snarky, creating various inventions for his own selfish intentions. However, in the end, he's well-meaning and does care about his friends and parents and at the end of the day, always saves the world.
• Kid Hero: Jimmy is only an elementary school student but always saves the day from trouble, albeit caused by his own mistakes.
• Lack of Empathy: Downplayed. Jimmy is often is blind to other people's feelings, no matter how obvious they may be. It's no wonder why he's better at making enemies than friends. That said, he usually is willing to fix whatever problems he made and his occasional callous nature isn't from malice but a lack of social skills.
• Little Professor Dialogue: Well, he does actually have an IQ of 210.
• Mr. Vice Guy: He does cause just as much problems as he fixes, and he isn't above rubbing his intelligence in some of the kids' faces (mainly Cindy's), but for the most part, he's a good kid whose heart is definitely in the correct position.
• My Greatest Failure: Establishing contact with the Yokians remains his biggest regret in life.
• Nerds Love Tough Schoolwork: Completely averted - in fact, Jimmy hates school, just like any normal American kid.
• Nice Job Breaking It, Hero: 99 out of 100 times, his inventions end up causing problems for everyone in Retroville, leading him to fix what he broke. As revealed in one episode, the majority of the Neutron extended family views him as the Black Sheep as a result (at least until he saves them from the new one... his Evil Genius baby cousin). In "The Incredible Shrinking Town", Libby remarks that Jimmy's endangered the town so often that she's just Stopped Caring.
• Nice Mean And In Between: The Mean to Carl's Nice and Sheen's In-Between. He's an Insufferable Genius to the highest degree whose inventions often lead to the problem of the week.
• No Social Skills: As a result of his smarts, he doesn't get people. He keeps really trying to improve on these.
• Odd Friendship: A boy genius whose closest friends are: an asthmatic hefty boy who's obsessed with llamas, a hyperactive Hispanic kid who's obsessed with a superhero, his academic rival/biggest bully/love interest & said rival's music loving sassy best friend.
• Pet's Homage Name: Jimmy designed and built his robot dog and named him Goddard in honor of rocket science physicist and inventor Robert Goddard. Especially apt when, in his first animated feature film, Jimmy is able to ride upon Goddard like a space bike.
• Pride: He can often be arrogant and overconfident.
• Primary-Color Champion: Jimmy wears blue jeans and a red shirt with a yellow atom on it, and is the main hero of the series. Fittingly, to contrast with Cindy, Jimmy's favorite colors are the three primary colors: red, blue and yellow.
• Properly Paranoid: He knew better than to trust the Yolkians in "The Eggpire Strikes Back".
• Puppy Love: With Cindy. Their roles ping-pong back and forth depending on the episode, but the general tone of their relationships is that they each have a crush on each other, but are too immature to act on it.
• Reed Richards Is Useless: It's shown that he's capable of inventing technology that could absolutely revolutionize the world, but he's just a kid, so he only uses them for trivial and frivolous reasons. Shown most egregiously with his "I Can't Believe It's Not Oil" machine, which composts trash into a clean-burning oil substitute and nets him a Nobel Prize. All Jimmy cared about was that he wasn't allowed to enter it in his school's science fair, and Hugh's the one who had the wherewithal to submit it to the Nobel Committee. Luckily, he eventually grows out of it (see below).
• Ridiculously Successful Future Self: In the 'good future' of The Tomorrow Boys, Jimmy is the first person to ever win the Nobel Prize in bulk. However, that was just a prediction, only Jimmy can make it happen.
• Science Hero: He embodies this trope for kids' shows, along with Dexter.
• Sesquipedalian Loquaciousness: A frequent user and abuser of advanced vocabulary.
• Slap-Slap-Kiss: With Cindy. They have a pretty heated rivalry that is punctuated by occasional affection that is heavily implied to be romantic.
• Small Name, Big Ego: Jimmy has a little bit of Pride despite the fact that his inventions usually go wrong and/or cause trouble, the fact that nobody likes him or treats him properly (to say the very, very least), and the fact that he's not very talented or skilled in other things besides science, building machines and gadgets, and having intellect (but even then, he doesn't have much common sense).
• Symbol Motif Clothing: His trademark atom emblem, which appears on the front of his shirt and nearly anything he invents.
• Strong Girl, Smart Guy: The Smart Guy to Cindy's Strong Girl. Cindy is smart but less of a Child Prodigy than Jimmy (a fact she resents), however she's more athletic than him and knows martial arts.
• Terrible Artist: While Jimmy is a scientific genius, he's absolutely atrocious in almost every field of the arts. His drawing skills are barely better than stick figures, his musical talent got him 8th place in a talent show with only seven acts, and his attempts at writing poems effectively inflicted a Logic Bomb on some of his machines. The only art-related achievement he has that doesn't involve cheating with his inventions is the fact that he's a better singer than Sheen.
• Took a Level in Dumbass: While still a genius in his own right, he tends to let his overconfidence and arrogance get the best of him quite a few times.
• Took a Level in Jerkass: In the spin-off TV show, he's more arrogant, show-offy, condescending, and selfish (albeit with a considerable good side). In the third season, however, he's much more abrasive and hostile. One could imply it's the result of having to deal with a lot of arch-foes and issues.
• Too Qualified to Apply: In "The Science Fair Affair", Principal Willoughby decides that Jimmy's high IQ and scientific knowledge gives him an unfair advantage over the other students, so he bans him from participating in future science fairs to give other kids a chance.
• TV Genius: He's a boy genius who is not only excessively prone to Techno Babble and Sesquipedalian Loquaciousness, but has invented time travel, faster-than-light warp engines, and the best candy in the history of all existence and everything.
• The Unapologetic: Whether Goddard suggests that Jimmy should apologies to his parents, Jimmy will always dismiss it out of his arrogance, as he thinks being a genius makes him always in the right. It normally takes some event to make him apologize.
• Vocal Evolution: In the pilot, the shorts and the movie, you'll notice that his voice was more nasally, scratchy and high pitched to match his dorky personality and sounded a lot more like Nergal Junior. Now his voice is more deep and clear.
• With Friends Like These...: Downplayed. Jimmy isn't a bad friend to Carl and Sheen, but he has used Carl as a guinea pig for many of his inventions with little concern for his friend's well-being in order to balance out Carl's own questionable treatment of Jimmy countless times.
• World's Smartest Man: Jimmy is considered the smartest human.
• Yank the Dog's Chain: One of Jimmy's signature flaws. When some of his inventions start off good, they backfire on him right afterward.

Carl Wheezer

Voiced by: Rob Paulsen, Wally Wingert (Jimmy Neutron Boy Genius console game)

Full Name: Carlton Ulysses Wheezer

Jimmy's shy, timid, nervous, and asthmatic best friend who has an unhealthy obsession with llamas and Jimmy's mom.

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• Abnormal Allergy: Carl has a ridiculous number of allergies, as do his parents. His father is once shown to have an allergy to ice of all things.^ExplanationIt's rare, but quite possible for people to be allergic to water, so it's not as big of a stretch as you might think.
• Accidental Hero: In "The Great Egg Heist", he accidentally mixes up the real jade egg with the fake decoy one after the inferred lasers trigger his allergies, and he ends up putting the real one back. This ends up saving everyone when Professor Calamitous tries to use the egg as a power source for his doomsday device, but the fake egg causes it to meltdown and explode. To be fair to Carl though, he knew there was a chance he mixed the eggs up and tried to warn Jimmy, but Jimmy constantly ignored him.
• Big Eater: You'd think having so many allergies would limit this, but no. Carl can chow down with the best of 'em and has a stomach of steel. Occasionally overlaps with Extreme Omnivore for laughs:
  Sheen: Carl, you're supposed to play with the toys in the silly meals. Not eat them.
  Carl: I know. But they always look so colorful and chewy.
• Big, Thin, Short Trio: The Big to Sheen's Thin and Jimmy's Short.
• Black Bead Eyes: He's the only character in the show to have these.
• Bring My Brown Pants: Carl has a tendency to soil himself.
  Carl: Mrs. Neutron, may I use your restroom? Because I really have to... never mind.
• Butt-Monkey: He's the Guinea pig to all of Jimmy's experiments. He's also the butt of gags such as him accidentally spraying his eyes with his inhaler.
• Cannot Keep a Secret: Whenever somebody has something they want hidden from others that Carl is in on, he always blurts it out. Make a second lunch so you still have one when a bully takes your first, Carl points it out and the bully destroys it. Take your friends to Egypt without the teachers noticing, Carl tells them the moment you get back. Disguise a brain drain helmet as a crown to save somebody who can read thoughts with the gained intelligence, Carl basically says exactly what they are doing in his head.
• Catchphrase: "My scapula..."
• Characterization Marches On: He eventually goes from being Jimmy's shy, asthmatic and introverted best friend to a more whiny and childish person.
• Cowardly Sidekick: Carl is much more introverted than his fearless best pal, Jimmy.
• The Ditz: In one episode, when Jimmy and Sheen shrink down and enter Carl's body. They enter his skull and get a close look at Carl's brain, it's so small that Sheen mistakes it for a walnut at first^note The gag comes up again in another episode where he, Jimmy, and Sheen get an X-ray that shows their brains. His brain is far tinier than the others.
• Dub Name Change: The Brazilian Portuguese dub changes his given name to "Caio", a notable Portuguese given name, as a form to make the public remember his name more easily.
• Dumber Than They Look: Carl Wheezer, despite having the big glasses, portly physique and breathing problems of a prototypical nerd, is only marginally smarter than resident Cloudcuckoolander Sheen, the episode "The Junkman Cometh" implying that he's even dumber when the titular Junkman scans their brains. Lampshaded on "Birth of a Salesman" when Jimmy's robot salesman says that Carl looks like a smart guy, and Carl remarks "Nuh-uh, it's just the glasses".
• Early Installment Character-Design Difference: Downplayed example. Carl stopped wearing suspenders after the movie.
• Extreme Omnivore: He eats newspapers and toys.
• Fartillery: Gets this in "The N-Men" (see Gasshole below).
• Fat Best Friend: Generally a straight mixture of a Type C (though not as big of a Cloudcuckoolander as Sheen) and a Type B (being shy). Which one dominates depends on the episode.
• Fat Idiot: To say the very least, he's overweight and isn't very bright.
• Gasshole: He has burped more than anyone else on the show (except for Jimmy's dad). In "The N-Men", he gets hit by some cosmic radiation that turns him into "Belch Boy", allowing him to unleash sonic blast burps by drinking seltzer or shaking himself really hard.
• Green-Eyed Monster: It is shown in "I Dream of Jimmy" and "Carl Wheezer, Boy Genius" that he'd really like to have Jimmy's life.
• Hollywood Tone-Deaf: His most attempts at singing something.
• Hypocrite: Out of the entire trio, he is the one most outspoken about how boys should not take interest in girls, even though he has hots for them just as often as Jimmy and Sheen do.
• It Runs in the Family: His allergies. Turns out his mother and father have various allergies too.
• Innocently Insensitive: Carl tries to give Jimmy a pep talk, but only says something that makes him upset.
• Jerkass Ball: Carl takes it in "Carl Wheezer, Boy Genius", which starts out as a standard "I lied to my pen pal" farce, then quickly escalates as we learn Carl lied about having Jimmy's life. It goes downhill as Carl not only has to masquerade as a boy genius, but he forces Jimmy to be his lowly assistant, or as Carl would put it: "My dimwitted assistant", which seems out-of-place for him to even say. Then Carl starts milking the moment by blaming him for everything. Even by the end, when Jimmy has saved his life at least three times, Carl is still blaming him and projecting his own insecurities onto Jimmy to boot.
• Likes Older Women: Carl has a crush on Jimmy's mom since Love Potion #976-J. He's also attracted to the class' teacher, Miss Fowl, who's in her fifties. At least and Beautiful Gorgeous too.
• Loose Lips: Sheen helps him a lot with this one. They're often the ones to reveal the secret plan to the enemy, generally via Suspiciously Specific Denial.
• Minor Injury Overreaction: Even the smallest tap on any part of his body will cause him great physical pain. He pretty much inherits this from the rest of his family as well.
• Nerd Glasses: Wears a pair of big glasses.
• Nerdy Inhaler: Carl uses an inhaler very frequently and is also allergic to almost everything.
• Nervous Wreck: He's a bundle of nerves constantly, due primarily to his weak constitution and nearly universal allergies.
• Never My Fault: He gives this treatment to Jimmy in "Attack of the Twonkies" and "Carl Wheezer: Boy Genius".
• Nice Guy: Despite his shyness and rather eccentric personality, he's still among the nicest of all the main characters.
• Nice, Mean, and In-Between: The Nice to Jimmy's Mean and Sheen's In-Between. He is always willing to help out Jimmy despite knowing his inventions could be dangerous on him.
• Ow, My Body Part!: He seems to have a really tender scapula.
• Precocious Crush: He has an ongoing crush on Jimmy's mom.
• Prone to Tears: For a fat guy, Carl is very thin-skinned.
• Shrinking Violet: He's generally shy and nervous, at least before his Flanderization.
• Sensitive Guy and Manly Man: The shy, cowardly Sensitive Guy to Sheen's superhero-obsessed Manly Man.
• Sickly Neurotic Geek: What else can you expect with a surname like 'Wheezer'?
• Stalker with a Crush: He becomes one to Jimmy's mom after being sprayed with Jimmy's love potion.
• Ungrateful Bastard: In "Carl Wheezer: Boy Genius", Carl steals Jimmy's life and constantly puts everyone in danger. Every time Jimmy saves him, Carl totally blames Jimmy and constantly treats him like a slave.
• Voice Changeling: In "The Incredible Shrinking Town", It was said he could do this from a ventriloquism lesson. The result was awesome. He was capable of impersonating Cindy's Mom's and Zix's voice perfectly.
• Vocal Evolution: In the pilot, shorts, movie and early episodes, his voice was more deep, nasally, and melancholy.
• With Catlike Tread: Carl seems to think he needs to loudly sing a theme song whenever he is working as a spy, which is the opposite of what a spy should do.
• With Friends Like These...: He and Sheen can act like this way towards Jimmy by laughing with Cindy and Libby when they bully him. Jimmy once told him and Sheen not to tell the other kids about his weather invention going haywire, but they told the kids anyway, causing said kids to be (albeit understandably) angry with Jimmy (though Carl justifies that this was due to peer pressure). Jimmy has, however, used Carl countless time as a guinea pig for his invention, so it pretty much balances out.
• Youthful Freckles: Has many freckles that match his red hair.

Sheen Estevez

Voiced by: Jeff Garcia

Full Name: Sheen Juarrera Estevez

One of Jimmy's best friends who is obsessed with the fictional superhero Ultra Lord. He's a hyperactive, stupid, eccentric, loud, energetic, and geeky Hispanic-American.

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• Accent Adaptation: In the Latin American dub, he speaks with a Japanese accent, possibly because the translators thought that he's Japanese-American, instead of Hispanic, and his name should be pronounced "Shin". Funnily enough though, Sheen was supposed to be Japanese, but since nobody could do anything Japanese sounding, Jeff Garcia came in and he was made Mexican.
• Ambiguously Bi: Even though Libby tends to be Sheen's main love interest and is heavily attracted to Beautiful Gorgeous, he has also shown to show a bit of attraction towards Jimmy, Carl and Jet Fusion as well.
• Attention Deficit... Ooh, Shiny!: More or less made explicit in "Sheen's Brain", wherein his ability to learn is limited by his concentration difficulties and hyperactive demeanor. This is what basically dooms his chances to pass the test that'll secure him staying in sixth grade, prompting Jimmy to fix it scientifically (temporarily).
• Badass Boast: In Sheen's Brain.
  I control the wind, and I shall rain fire down from the heavens! Goodbye Sheen the overlord. Hello Sheen the God!
• Berserk Button: Do NOT call Ultra Lord a doll. Or mock Ultra Lord in any way. And definitely don't mess with his precious Libby.
  Sheen: Guys, what're you so worried about? Ultra Lord's gonna be here any minute.
  Cindy: Ultra Lord's not coming you, ding-dong! The Yolkians lied to you!
  Sheen: WHAT?! Then they have awakened the wrath of Sheen!
• Beta Couple: With his sweet princess, Libby.
• Beware the Silly Ones: He actually cares about Libby more than Ultra Lord and was more than willing to fight Yoo-Yee to get her back.
• Big, Thin, Short Trio: The Thin to Carl's Big and Jimmy's Short.
• Book Dumb: An exaggerated example, given he's very incompetent in school, yet makes up for it with his encyclopedic knowledge of superheroes like Ultra Lord.
• Butt-Monkey: He suffers a fair amount of physical abuse. He is also sometimes used to test Jimmy's experiments, but he actually enjoys this.
• Character Exaggeration: Some people may not know this, but in the movie, he was fairly intelligent and less hyperactive. In Season 3, he's more loud and ignorant. In Planet Sheen, all of his serious traits are totally erased; changing him from his nerdy and hyperactive self to an obnoxious prick.
• Character Tic: Tends to go cross-eyed whenever overexcited or shocked about something.
• The Chosen One: Sheen happens to be this for the monks of Shangri Llama, who regard him as "he who puts foot behind head".
• Cloudcuckoolander: In a minor but interesting play-off of the idiot sidekick shtick. Sheen isn't exactly stupid (at least before Flanderization set in); he's just very, very scatterbrained.
• Comically Missing the Point: In "Maternotron Knows Best", Robot Judy gives Sheen and Carl application forms. Sheen's question is "Jimmy falls in the playground and breaks his leg. What do you do?" His response: "Well that's a stupid question. They don't even tell you which leg it is".
• The Ditz: His IQ is 32. Rule of Funny is presumably the only reason he's able to function at all.
• Drunk with Power: When his intelligence is increased in "Sheen's Brain".
• The Friend Nobody Likes: Sheen constantly annoys everyone with his ramblings about Ultra Lord, low intelligence, annoying shouting and the fact that he can be insensitive. However, Jimmy and Carl still consider him to be a good friend and the three of them are quite close.
  Sheen: Hey Robot! If the Junkman turns your parents into gravadiscs, can I have one?
  Jimmy: Sheen!
  Sheen: But they look so cool.
  Robot: [to Carl] I don't like Sheen.
  Carl: Tell me about it.
• Genius Ditz: It should be noted that he seemingly on his own created an entire website dedicated to Ultra Lord at a time when doing such a thing required some programming knowledge. Said website claimed Ultra Lord was the father of America (and the whole planet).
• Goofy Print Underwear: Limited Edition Ultra Lord Underwear! Only available in Japan!
• Held Back in School: It's revealed in "Operation: Rescue Jet Fusion" that he's been in the same grade as his friends for two years.
• Hidden Depths:
  • Despite scoring a quadruple F-minus on a U.S. history exam, in "Who Framed Jimmy Neutron", he is aware that Jimmy Carter is the 39th President of the U.S., showing that he has at least some educational knowledge of U.S. history.
  • He has a one-off line about how he, "sabatoged [his] highly scientific brain early on with cartoons and sugar" to avoid the struggles of being a genius. Essentially he pulled a less-sci-fi version of Jimmy's brain-drain helmet scheme.
  • In "Who Framed Jimmy?", Sheen mentions he's taken bear-wrestling classes, as he was able to wrestle a entire wild grizzly bear without a scratch on him.
    Sheen: Man, those bear-wrestling classes my dad made me take sure paid off.
• Hollywood Tone-Deaf: His singing is so bad, it actually puts the music-hating Twonkies to sleep.
• Innocently Insensitive: Thanks to his short attention span and low intelligence, Sheen tends to say very insensitive things to Jimmy and Carl.
• Jerkass Ball:
  • In "Sheen's Brain", he becomes arrogant and rude towards everyone after becoming a genius and that's before he gains telekinetic powers, plots to plunge all of Retroville into darkness and sadistically tortures Jimmy and Carl. When he brutally strikes them with a lightning bolt, he realizes his new powers have turned him into a monster and decides to go back to normal. This also counts as Temporarily a Villain.
  • In "Jimmy for President", Sheen blackmails Carl with an embarrassing photo from Ike's birthday party if he doesn't vote for him. When Sheen's plot is exposed, he is disqualified from the election (along with Jimmy and Libby for the same reasons).
  • Sheen is often insensitive to people's feelings, though it alternates between his being too scatterbrained to pick up on emotional ques or too thick-skinned to take much note of them.
• Jerk with a Heart of Gold: Sheen has a habit of being arrogant, insensitive, and obsessed with his self-interests, especially his obsession with Ultra Lord. He is still supportive and loyal to his friends and seems to love Libby and his dad.
• Keet: He's very energetic.
• Large Ham: Pretty much. He has absolutely No Indoor Voice, always yells unnecessarily, and behaves in a very over-the-top, overly energetic demeanor. He also has some dramatic moments, like in the Jimmy-Timmy Power Hour when he finds out that Timmy Turner isn't Jimmy.
  Sheen: SHE'S A WITCH I TELLS 'YA!! BURN HER! BURN HER!!
• Loony Fan: He's obsessed with cartoon superhero Ultra Lord.
• Meta Guy: A Running Gag in the later seasons has him predict that an adventure is imminent before any of the other characters even get to that point (so much so that him saying, "To the lab!" early becomes kind of a catchphrase). In Stranded, for example, he can tell it just from the fact that Jimmy and Cindy are arguing:
  Sheen: Just a little longer, Carl. Our adventure should start at any minute.
  Carl: What adventure?
  Sheen: You'll see...
• Misery Trigger: He can't stand the thought of Ultra Lord being cancelled.
• Missing Mom: According to the creators, she died when Sheen was too young to remember her.
• Nice, Mean, and In-Between: The In-Between to Carl's Nice and Jimmy's Mean. He's the wackiest and most high-spirited guy of the group, but does have a bit of an ego like Jimmy and tends to be a bad friend in certain circumstances.
• No Indoor Voice: Sheen yells all the time, especially in Season 3.
• Odd Couple: Him and Libby. He's so Hollywood Tone-Deaf the Twonkies were unaffected and she's the biggest music geek in town.
• Plucky Comic Relief: He serves as the funny sidekick on the show.
• Puppy Love: With Libby. It's actually somewhat more explicit compared to Cindy and Jimmy, largely because Libby is more emotionally mature and Sheen is more open about his feelings.
• Red Oni, Blue Oni: The hyperactive, energetic red to Nick's savvy, jaded blue.
• Sensitive Guy and Manly Man: The superhero-obsessed Manly Man to Carl's shy, cowardly Sensitive Guy.
• The Slacker: Watches Ultra-Lord while trying to do his homework.
• Teacher's Unfavorite Student: Miss Fowl has a particular dislike towards him due to his obsession with Ultra Lord, to the point where he showed off his action figure of him for show and tell seven weeks in a row, and because he is extremely Book Dumb, to the point where he once scored a F---- on a test (one of his answers was that Ultra Lord was the father of the United States, which was on the official Ultra Lord website). She is also not above insulting his terrible singing voice, to the point where after she gives him a solo in the school choir to thank him for saving the town from the Twonkies (since they like terrible music but hate good music), she locks him in a sound-proof booth. In "Journey to the Center of Carl", when all of her students are too sick to go to school thanks to Jimmy's sick patches, she admits that she misses all of her students, except for Sheen.
• Too Kinky to Torture: Sheen seems to get a kick out of being electrocuted. In "Krunch Time", after Carl gets electrocuted trying to remember which door has cheese behind it, Sheen is eager to take his turn just so he can touch "the shocky door" again. At the end of the episode, when Jimmy sabotages his perfect candy by having it electrocute people, Sheen is the only one who enjoys it. At the end of "Who's Your Mommy?", he, Jimmy and Carl go to Planet Shmengy to celebrate the birthday of Shmengo, Carl's adopted son who's an alien jellyfish. After Carl gets electrocuted from hugging Shmengo, Sheen hugs Shmengo and gets electrocuted as well. He then hugs Shmengo a second time just so he can get electrocuted again.
• Vibrant Orange: Sheen is very loud and peppy. As Vibrating Lad, he wears an orange costume.
• Vibration Manipulation: In "The N-Men", Jimmy and his friends are exposed to cosmic radiation that grants them superpowers. Sheen, who was in a vibrating massage chair during this incident, gains the ability to vibrate and move at super speed. Appropriately, he takes the codename "Vibrating Lad".
• Vocal Evolution: In the film, his voice is deeper, and he's less prone to over-the-top outbursts. In the TV series, it's noticeably higher and he's more consistently hyperactive.
• We Want Our Idiot Back!: In "Sheen's Brain", Sheen is in danger of being held back in school after failing a recent history test, requesting Jimmy to create a device to greatly boost Sheen's IQ. While great at first, Sheen rapidly becomes more intelligent and arrogant as time passes, to the point where he develops psychic powers and declares himself a god. However, after realizing that he hurt Jimmy and Carl who were trying to help him before his head explodes, Sheen chooses to willingly decrease his IQ to turn himself back into his idiot self, apologizing for his actions.
• Wide-Eyed Idealist: He believed that there was goodness in Tee and was proven right.
• With Friends Like These...: He and Carl can act like this way towards Jimmy by laughing with Cindy and Libby when they bully him. Once, when Jimmy told him and Carl not to tell the other kids about his weather invention going haywire, they told the kids anyway, causing said kids to be (albeit understandably) angry with Jimmy.
• With Great Power Comes Great Insanity: When he becomes a genius, he gains telekinetic and psychic powers and plots to destroy all of Retroville. Not to mention he nearly kills Jimmy and Carl.

Cindy Vortex

Voiced by: Carolyn Lawrence

Real name: Cynthia Aurora Vortex

Jimmy's rival and female counterpart, who has a crush on him. Not that she'll admit it.

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• Abusive Parents: Somewhat ambiguous. Mrs. Vortex is portrayed early in the show as strict, snooty, and likely responsible for Cindy's ambition, competitiveness, the huge number of extracurricular activities, and her insecurities (Mr. Vortex is The Voiceless and mostly a nonentity where the stories are concerned). That said, she was portrayed more kindly in later episodes, to the point that in "Win, Loose, Kaboom", she is the first to suggest that the Retroville parents start working on helping their children instead of just standing and watching. Both the movie and its video game adaptation confirm that the Vortex family members genuinely love each other.
• Academic Alpha Bitch: She lost her reputation as the smartest kid at her old school when she moved into the house across the street from Jimmy, whereupon Cindy, now runner up, began a rivalry with him.
• Academic Athlete: The smartest student after Jimmy and knows karate enough to kick asses.
• Action Girl: Cindy practices karate.
• Actor Allusion: Cindy isn’t the first book-smart, highly competitive, and martial arts practicing character voiced by Carolyn Lawrence.
• Aesop Amnesia: How many times has Cindy learned not to take her friends for granted or act obnoxiously clingy towards Jimmy or give into false flattery?
• Attention Whore: Cindy feels the need to constantly remind everyone of how "beautiful, talented, and perfect" she is.
• Badass Adorable: A young girl who's also a skilled martial artist.
• Badass Bookworm: Other than being the second smartest kid in town, Cindy is more athletic than Jimmy, who is a regular Bookworm, and practices a lot of martial arts sports.
• Bad Liar: Cindy is the worst liar in the world.
• Because You Were Nice to Me: Cindy holds a particular fondness towards Timmy Turner because he actually treats her with respect. Even after learning Timmy lied to her about being a genius so she could like him, she still considers him a decent guy because he was genuinely sorry about it.
• Cannot Spit It Out: Cindy's extremely cautious when it comes to saying things she might regret afterward so she usually avoids it when she can. And when she knows she should apologize to Jimmy or otherwise acknowledge his intellect or skill, it's bound to come out after a prolonged period of awkward silence or "Neutron, I hate to say it but...". Obviously applies to revealing her true feelings about him as well.
• Chic and Awe: Cindy complains about Jimmy being best man at Jet Fusion's wedding to Beautiful Gorgeous in "My Big Fat Spy Wedding", only to stop stunned as Jimmy shows up in a handsome tux. Libby has to snap her out of it.
  Cindy: So Neutron's the best man? Yeah, more like the best NERD! I bet he'll look like a total... (Jimmy shows up outside the church in a tux. Cue fade to pink background, eye-hearts and hair patting) ...HUNKMUFFIN.
• Clingy Jealous Girl: She doesn't like seeing Jimmy showing any interest in other girls, most notably Betty.
• The Corruptible: She tends to get easily flattered by the villains into helping them, mostly to spite Jimmy.
• Deadpan Snarker: She's often prone to sassy remarks.
  • For example "Beach Party Mummy" has this exchange:
  Jimmy: I don't understand it. I can't seem to find the lost tomb!
  Cindy: Duh! That's why they call it the "lost tomb", not the "here it is tomb, come inside and have a milkshake"!
• Defrosting Ice Queen: Towards Jimmy over the course of the show, as her affection towards him becomes more evident.
• Depending on the Artist: Oddly, she has two distinct designs depending on the media she's in. Her movie design gave her a pink shirt and pigtails, while the show redesigned her to wear a green tank top and a ponytail. Despite her show redesign being established early on, various tie-in games retained the original movie design to the point where it makes up the majority of her video game appearances, and she ironically wouldn't use her show design in games until after the show already ended (such as in Globs of Doom or Nickelodeon Kart Racers 3).
• Expy: Of Helga Pataki. Both of these tomboyish blonde lasses each harbor crushes on the main protagonist, but act antagonistic and bully them whenever they're present in order to hide it. Cindy even resembled Helga quite a bit in the early shorts and the pilot movie, sporting two pigtails and wearing a pink shirt similar to Helga's pink and white dress. Her altered appearance in the series proper was likely done to differentiate her from Helga.
• Flanderization: In the movie, she was revealed to be a lot kinder than she seemed and she and Jimmy got along better as a result by the film's end. In the series, she's become more stubborn and she and Jimmy fight more.
• Genius Bruiser: Though not as intelligent as Jimmy, Cindy is still smart in her own right and is also a skilled martial artist.
• Girlish Pigtails: In the movie and shorts before trading it to a ponytail.
• Goofy Print Underwear: Polka dot panties.
• Green and Mean: She often wears a green outfit and is quite sassy and condescending towards others (especially Jimmy).
• Green-Eyed Monster: Does the trope both figuratively and literally (with actual green eyes).
  • She was the smartest kid in her old school until she moved into town and met Jimmy.
  • It is also shown that she is jealous of Betty Quinlan, and not just because Jimmy likes her.
  • In "Beach Party Mummy", she suspiciously asks "What's going on?" when Jimmy holds Libby's hand (after he figures out that she can trick the mummies into sparing them due to being a descendant of a female Pharaoh).
• Hint Dropping: Unfortunately, Jimmy seems to permanently be holding the Idiot Ball when it comes to interpersonal relations.
• Hollywood Genetics: She has blond hair and green eyes. Neither of her parents are blond (Her mom has black hair and her dad has brown hair) and her father's brown eyes would likely have dominated her mother's green eyes.
• Idiot Ball: Whenever the villains try to manipulate her into helping them with false flattery.
• I Just Want to Be Special: She actually admires Jimmy, is very fond of him and secretly wants to be as brilliant and smart as him. Also counts as Inferiority Superiority Complex.
• It's All My Fault: In "The N Men", when she realizes that her mistreatment towards Jimmy has turned him into a hulking jerk monster.
• Jerkass Has a Point: Cindy is not entirely wrong about Jimmy always causing trouble for the town (and sometimes, the world) and always points out the flaws in his "brilliant plans". In "The Science Affair", although more to make herself win, she's not entirely wrong that Jimmy should no longer be permitted to participate in school science fairs since he wins every year and is the therefore Too Qualified to Apply.
• Jerk with a Heart of Gold:
  • Cindy is bossy, spoiled, stubborn and self-centered, but underneath all that, she is a genuinely good person, but doesn't want anyone to know that.
  • She is deeply infatuated with Jimmy, looks up to him and wants to be as brilliant as him. This is pretty much the main reason why she always tries to poke fun at him or otherwise make him angry. Works both ways.
  • She enjoys taking care of pets, plants and little babies.
  • She doesn't like it when Jimmy is emotionally crushed, heartbroken or depressed and usually goes to comfort him.
• Jerk with a Heart of Jerk: In "Who Framed Jimmy", she doesn't care that Jimmy has been sent to prison and tries to turn him in to get the reward money.
• Kung-Fu Kid: Cindy practices karate. She goes to competitions, is sometimes seen in her gi, and although we're never told what level she's at, based on some of her flips, she's probably a black belt.
• Laser-Guided Karma: In the Christmas Episode "Holly Jolly Jimmy", she and Libby get coal for Christmas as punishment for turning Retroville against Jimmy after he accidentally ruins Christmas by scrambling Santa Claus' atoms. It helps that Jimmy did his best to fix his mistake and that Cindy and Libby kept on ragging on Jimmy even after he apologized for his blunt arguments that Santa doesn't exist.
• Last-Name Basis: Even though she uses Jimmy's first name plenty of times, she often calls him by his last name (or the "Nerdtron" nickname she came up with) and even when she warms up to him towards the end of the show, it's not usual to hear a "Jimmy" coming out of her mouth, possibly because old habits die hard or possibly because he's gotten a bit more irritable around her. In all fairness, Jimmy himself does call Cindy "Vortex" every once in a while, mainly when he's annoyed.
• Laugh of Love: She sometimes laughs when she's having romantic moments with Jimmy, most notably in the episodes "Love Potion 976/J" and "Stranded".
• Little Miss Snarker: In "Trading Faces":
  Jimmy in Cindy's body: Don't give Cindy my astounding ability to create and build pioneering technologies, okay?
  Cindy in Jimmy's body: Oh yeah, like I'd want to invent a toilet in a briefcase!
• Loving Bully: She picks on Jimmy but she only does this to mask her love for him.
• Never My Fault: She gives this treatment to her friends when she causes the problem. Particularly in "Vanishing Act", which Jimmy understandably calls her out on.
• Nice Job Breaking It, Hero:
  • In "The Eggpire Strikes Back" she tells King Goobot how to get inside Jimmy's lab after learning it from Carl and Sheen. Partly subverted since for all she knows they just want to help her in being able to compete with Jimmy on an equal footing by means of building a lab of her own, though she's dumb enough to trust the Yolkians (and so is everybody else in town, except Jimmy). When she realizes that her actions put the whole Retroville in danger, she is the first to call on the others to believe Jimmy and help him bring down Poultra.
  • "The N Men" has her acting uncharacteristically harsh to Jimmy and she refuses to listen to his warnings about misusing her powers. Fed up with Cindy's nasty attitude and how she treated him, Jimmy transforms into a hulking jerk monster. When she sees that the army is after him, she realizes that this is all her fault and decides to make amends by helping him. Later as she's falling unconscious, she gets down on her knees and apologizes to Jimmy for hurting his feelings and attempts to tell him how she really feels, changing Jimmy back to normal.
  • "Vanishing Act" has her resentment towards Betty going critical and she causes Jimmy's magic box to overload and send herself, Betty, Carl, Jimmy and Sheen into some strange world. Jimmy finally gets the pleasure to call her out for it.
  • In "Normal Boy", Cindy coldly tells Jimmy to leave for college already because she's so jealous of Jimmy always stealing her thunder at Show-and-Tell. Because Jimmy took this criticism to heart, he dumbs himself down (literally, using a brain drain helmet) just when he's needed to deflect a meteor headed for Retroville, forcing Cindy to help Jimmy regain his intelligence.
  • "King of Mars" has her defecting from the gang to join Eustace. Again, subverted because the only reason why she does it (and the very argument Eustace uses to convince her) is to make Jimmy finally take notice of her, even though she was Too Dumb to Live. That's also why she is Easily Forgiven later on.
• Nice, Mean, and In-Between: She's the Mean to Nick's Nice and Libby's In-Between. She always rebels against Jimmy, but slowly grows more affectionate to him over the course of the series.
• Out-of-Character Moment: In the Fairly OddParents crossover trilogy, she acts totally unrealistic and airheaded when Timmy is around and is blind to all of his lies and she even makes stupid assumptions. She doesn't even care that Jimmy and Timmy were practically killing themselves because of her.
• Pink Means Feminine: Wears pink sneakers and, as seen in the first episode, light-pink panties. Also wore a pink shirt in the shorts and movie. She also decorates her room pink.
• Pride: Like Jimmy, this is one of her trademark flaws. Cindy never admits her mistakes and always tries to find excuses to blame her friends.
• Puppy Love: With Jimmy. It's framed by her dislike of boys in general and of Jimmy in particular because of his constantly showing her up, but several episodes show that she has a pretty huge crush on him.
• The Rival: To Jimmy, primarily in academics, but also in everything else they can compete in.
• Rivalry as Courtship: Jimmy and Cindy each have their own respective crushes in the beginning of the series (Betty and April for Jimmy, and Nick Dean and Timmy Turner for Cindy) while nursing their own rivalry with each other. By the end of the series though, it's clear where their relationship stands.
• Secondary Color Nemesis: She is Jimmy's main rival and wears a green tank top, with her favorite colors consisting of green, purple and orange.
• Slap-Slap-Kiss: With Jimmy. In some episodes, they're bitter rivals. In others, it's Puppy Love.
• Spoiled Brat: Cindy can be very bratty if she doesn't get what she wants.
• Strong Girl, Smart Guy: Strong Girl to Jimmy's Smart Guy. Cindy is smart but less of a Child Prodigy than Jimmy (a fact she resents), however she's more athletic than him and knows martial arts.
• Tank-Top Tomboy: Cindy wears a green tank top and is a Passionate Sports Girl who knows karate.
• Tomboy and Girly Girl: The Tomboy to Libby's Girly Girl. Downplayed in later seasons, but Libby is still into more "girly" pastimes like music and fashion, while Cindy is a Passionate Sports Girl with a tomboyish streak.
• Tomboyish Ponytail: In the TV series. She has Girlish Pigtails in the movie. Accordingly, she's more tomboyish in the former.
• Tomboyness Upgrade: From the movie to the series. While shown to be a good fighter during the climactic battle in the movie, the series upgrades her skills to the point that she can compete even with a member of a warrior race of aliens, and in general puts more emphasis on her passion for karate. To match, she trades her Girlish Pigtails for a Tomboyish Ponytail.
• True Companions: With Libby and Brittany.
• Tsundere: Type A, obviously. In the movie she explains that she only became one to Jimmy because she was jealous of his better grades and she hates his tendency to show off his intelligence on every given occasion.
• Vocal Evolution: As the series went on, Cindy's voice got a bit harsher and she developed a slight Texan accent akin to that of Sandy Cheeks, another character voiced by Carolyn Lawrence.
• Women Are Wiser: Every once in a while, especially seeing as Jimmy tends to lose sight of the bigger picture and waste time using his inventions even when simpler means would suffice. However, since she's at least just as stubborn as Jimmy, her taking the helm doesn't always prove to be the best idea either.
• Yank the Dog's Chain:
  • In "The Science Fair Affair", she loses the trophy even after she helped save the day.
  • In "Win, Lose and Kaboom", April ruins her and Jimmy's big chance to kiss.
  • In "Attack of the Twonkies", after Jimmy and Sheen save the town, Sheen steals her spot in the school chorus.
• Yin-Yang Bomb: Cindy tries to invoke this spiritually in the film by practicing Tai Chi while drinking purple flurp soda.
  Cindy: Tai Chi promotes wellness, relaxes, and rejuvenates the body. Whereas purple flurp, being ninety-eight percent sugar, creates tension and a temporary rush of energy and mood swings. I figure if I do both of them together, I achieve perfect balance.

Libby Folfax

Voiced by: Crystal Scales

Real name: Liberty Danielle Folfax

Cindy's best friend and Sheen's love interest. The love of Libby's life? Music, the funkier the better. And she doesn't just listen, she also plays the keyboard, DJs, and can throw a high note that would give most opera singers a run for their money.

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• Beta Bitch: She plays this role to her best friend Cindy.
• Beta Couple: With Sheen.
• Big Sister Mentor: Libby serves as a big sister to Jimmy and is always trying to get him to come out of his shell.
• Cannot Tell a Lie: Which usually makes it hard for her to keep secrets or for her to go with Jimmy's brilliant plans. However, Libby does lie in "Jimmy for President" and "Attack of the Twonkies". Naturally, her friends are shocked by this.
• Character Development: Libby used to be more of a sidekick to Cindy, but she soon enough became more distinct and evolved into the group's Deadpan Snarker and most sensible and levelheaded member.
• Cheaters Never Prosper: In "Jimmy for President", she tries to buy Carl's vote and even lies to him. At the end, Libby (along with Jimmy and Sheen) is disqualified from the election as a result.
• Costume Evolution: In a reverse of how Cindy originally sported a t-shirt to a tank top, Libby wore a sleeveless green dress for the movie and first season. After her haircut, Libby wears a pink shirt with blue jeans.
• Deadpan Snarker:
  Sheen: Don't worry, Libby. When I'm elected, you can still be my First Lady.
  Libby: Get a life, Sheen.
• Famous Ancestor: In the Egypt episode, Libby discovers that she's the descendant of the Egyptian Queen Hasabataslapya.
• Gasshole: Becomes one after eating the Belch Boy packet in "The League of Villains", even to the point of making a dance out of her burps.
• Give Geeks a Chance: Both in telling Cindy to be honest with Jimmy and her own involvement with Sheen.
• Hidden Depths: In "My Big Fat Spy Wedding", she has an official business performing at weddings and can even play the piano.
• Important Haircut: Libby gets one in the Beach Party Mummy episode to fool a bunch of mummies that were chasing the gang. She keeps the new look for the remainder of the series.
• Incredibly Long Note: Turns this into a Chekhov's Gun in "The Great Egg Heist".
• Invisibility: She gained this power along with the ability to generate force fields in "The N-Men" episode.
• Jerkass Ball: In "Lady Sings the News", Libby betrays her friends, exploits their secrets to the press and even blackmails people into waiting on her. Later, when she finds out the town is gonna kill Carl, she sees the error of her ways and apologizes to her friends.
• Nice, Mean, and In-Between: She's the In-Between to Nick's Nice and Cindy's Mean. She's not as mean as Cindy, but is more impulsive than Nick.
• Not So Above It All:
  • Just like Cindy does with her feelings for Jimmy, Libby sometimes denies her feelings for Sheen.
  • Sometimes, she is shown to like Ultra Lord as well.
  • When she gets her music taken from her, she starts sobbing like a baby.
• Odd Couple: Her and Sheen. She is the biggest music geek in town, he's so Hollywood Tone-Deaf the Twonkies were unaffected,
• O.O.C. Is Serious Business: Whenever she lies. And if she stops listening to music, you know something is wrong.
• Only Sane Woman: She's the most levelheaded character in the series (along with Judy).
• Pink Means Feminine: Her new design includes a pink long-sleeved shirt.
• Puppy Love: With Sheen. She returns his affections subtly and hesitantly at first, but she's the first one to call herself his girlfriend.
• Sassy Black Woman: She's Cindy's sassy black best friend.
• Shipper on Deck: She's FOREVER pleading with Cindy to just tell Jimmy how she feels and get it over with! Can you blame her?
• Token Black Friend: The only black girl in her group of friends and hangs around the white Cindy specifically.
• Tomboy and Girly Girl: The Girly fashionista to Cindy's athletic Tomboy.
• Tomboy with a Girly Streak: She adjusts really quickly to becoming "Burp Girl" in "The League of Villains", even proving better at using the sonic-blast burps than Carl did in "The N-Men". She's sassy, loves hip-hop and electronic gadgets, and wears jeans (as opposed to the movie, where she has more a Girly Girl design), but she also likes fashion and has a pink shirt.
• True Companions: With Cindy and Brittany.
• Women Are Wiser: Compared to her boyfriend, Sheen.

Goddard

Voiced by: Frank Welker

Jimmy's robot dog and lab assistant.

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• Badass Adorable: Goddard's appearance, loyalty, and playful nature is just adorable. He's also tech-savvy and very useful when he is needed at any time.
• Benevolent A.I.: Goddard is by far the only robotic invention of Jimmy's who hasn't gone haywire or turned against him (except when Timmy corrupted him with a video game).
• A Day in the Limelight: Goddard is by all means a main character, but the only episode that gives him the focus is "Best in Show", one of the last ever aired.
• Do-Anything Robot: He does eleven million and four things! Except clean up after himself.
• Eating Machine: There's several occasions where he also eats human foods like ice cream.
• Evil-Detecting Dog: In "N-Men", Goddard watched in fear as Jimmy transform into his Orange Hulk form once his anger finally overtook him. hiding behind some containers.
• Heroic Dog: Goddard is a good boy. He is lovable, constantly loyal to Jimmy, playful, kind, and just downright adorable.
• Jaw Drop: He has this moment after seeing Jimmy dressed up for his date with Cindy. Being a robot, his jaw literally dropped.
• Morality Pet: To Jimmy. Both figuratively and literally. While, at his worst, Jimmy will treat his friends like lab rats and his family as an afterthought, Goddard always brings out the best in him. He also acts as Jimmy's conscience, and always suggests doing the right thing when Jimmy asks him for options. He's also how Timmy was able to relate to Jimmy on care for (what Jimmy believes to be) artificially intelligent beings.
• Non-Human Sidekick: To Jimmy. A double example, being both a robot and a dog.
• One-Word Vocabulary: "Bark!" and no that's not an onomatopoeia, Goddard actually says "bark" as it's spelled out.
• Robot Buddy: Jimmy's mechanical canine and best friend.
• Robot Dog: A robotic dog invented by Jimmy himself.
• Self-Destruct Mechanism: His "plays dead" command is this. Goddard can reassemble himself despite his core combustion. This ability is vital to defeat Eustace's Robo Adaptoy.
• The Speechless: Except in the movie, where his options for Jimmy are read in a robotic voice.
• Team Pet: A robot dog, who happens to be the gang's mascot.
• Undying Loyalty: He loves and is entirely loyal to his owner and creator, Jimmy. In "Krunch Time", he pulls Jimmy out of a crisis when the whole town (which includes Jimmy's own parents and friends) attempts to enslave him when he creates a candy so addictive they can't stop eating it.

Hugh Neutron

Voiced by: Mark DeCarlo

Real name: Hubert Beaumont Neutron

Jimmy's father, who averts the "Father Knows Best" ideal. Nevertheless, he's a chipper, upbeat family man who always has time to dispense words of wisdom for Jimmy, even if most of the time those words are better left ignored. He also has an obsession with ducks.

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• Adults Are Useless: Hugh is probably one of the biggest idiots in Retroville. In fact, he messes with Jimmy's inventions all the time.
• Breakout Character: Hugh was announced as Downloadable Content for Nickelodeon All-Star Brawl before Jimmy himself, likely as a result of his then-recent boost in popularity.
• Bumbling Dad: Boy, is he ever. Many times, Hugh would screw up one of Jimmy's inventions because of his moronitude and him being the typical, dim-witted bumbling father.
• Chaotic Stupid: Sometimes, such as abusing Jimmy's rewind remote for his own personal amusement, arousing the anger of the townspeople affected by his antics.
• Cloudcuckoolander: Quite possibly the largest one in the series due to how much he's shown to be the weirdest person in Retroville, mainly because of his striking confidence.
• The Ditz: He's a nice moron at the very least.
• Empty Nest: In "Jimmy Goes to College", he misses Jimmy so much he buys fleas which he all names Jimmy (or variations thereof) to fill the void Jimmy left behind.
• Flanderization: While he was a bit eccentric in the original movie, the show made him a straight-up cloudcuckoolander.
• Foolish Husband, Responsible Wife: He's the Foolish Husband to Judy's Responsible Wife. He's a goofball who has a strange obsession with ducks and often tells nonsensical pieces of advice. He's also messed up Jimmy's inventions on several occasions.
• Gasshole: Even without drinking the Burping Soda, Hugh has burped more than anyone else in the series, including Carl.
• Genius Ditz: While he doesn't have his son and wife's scientific and technical intelligence, Hugh actually has an insane memory when it comes to his passions like ducks and pies. He was even able to answer an obscure trivia question involving a space soap opera he binge-watched by spitting out the plot without even stuttering or pausing as if he had a mind-map with it all right in front of him. It is also important to note that Jimmy actually gets his intelligence from his side of the family, not his mother's.
• Good Parents: Despite his bumbling nature, he's shown to genuinely love and care for his son and is completely supportive of his interests. He's also the one who helps Eustace Strych's father find the will to assert himself when his son misbehaves.
• Happily Married: To Judy. In many of their scenes together they're usually shown being lovingly playful with each other and rarely fighting.
• In Spite of a Nail: In the Alternate Universe where he invested in McSpanky's, he still married Judy (despite the fact that he's wealthy, and can have any wife he wanted).
• Jerkass Ball: Twice as a result of Jimmy's inventions.
  • The first is when Jimmy altered the past so that his dad would invest his only money ($50) into the then non-popular restaurant McSpanky's, to make his parents rich and allow him to get an expensive set of encyclopedias that he wants. Unfortunately, along with Judy, he becomes a snobby rich man with no interest in his son, forgetting his name and offering him some money to leave. He even refuses to help pay for a lifesaving operation for his father merely because he does not want to lose any money.
  • The second is when Jimmy uses a machine to turn him cool (and prevent him from embarrassing him at the Fathers Day performances at school). He becomes super popular with the town, but never wants to spend time with Jimmy or Judy anymore and plans to leave them to go on a World Tour as a pop star. He even initially refuses to save his son's life before his parental instincts finally kick in and revert him back to normal.
  • The third is when he and Carl's dad engages in a feud joined by their wives, he's more unreasonable and crueler towards Jimmy in order to forbid him being friends with Carl then usually when his feuding with his neighbor clouded his better judgment with him going so far of degrading into an Abusive Parent and a Fantasy-Forbidding Father by banning Jimmy from inventing anything because so he could make the feud last.
• "Jump Off a Bridge" Rebuttal: Twisted.
  Jimmy: But Dad! All my friends are going!
  Hugh: I know, Son, but if all your friends were named Cliff, would you jump off them?
• Leitmotif: He has his own character theme in the series that's usually played during moments when he wants to bond with his son.
• Manchild: Probably the least intelligent person in Retroville, rivaling Carl and Sheen (who funnily enough, are fans of him). The guy's obsessed with ducks and pies, comes up with childish theories, and acts as if he's a ten-year-old. The only person who could rival his childishness is probably Timmy Turner's dad.
• Metaphorgotten: This along with his acts of making Ice-Cream Koan sayings or his unsophisticated knowledge to his sayings, some of his analogies can make little sense.
• Never My Fault: He gives this treatment to Judy when he sends the town back in time using Jimmy's Wormhole Generator. She does call him out on this.
• Nice Guy: Despite being a Bumbling Dad, he is good-natured and a caring father.
• Nice Job Breaking It, Hero: Sometimes he causes the episode's problem.
• Obliquely Obfuscated Occupation: Eventually averted when we learn he's a car salesman.
• Papa Wolf: He's got his awesome moments in the TV series, from fighting mutant crabgrass to trying to scare off a bear with a torch. Hugh may be an idiot, but you do not threaten his son.
• Simpleton Voice: Although he doesn't completely have this dialect, his cadences would still have these in Hugh's mildly goofy voice to match his bumbling nature.
• Simpleminded Wisdom: Usually Played for Laughs when Hugh would give advice to Jimmy in such a hilarious manner because of how unimportant it usually is and how Hugh would hilariously believe that his own advice helps at all, being the bumbling person that he is.
• Smart People Wear Glasses: Inverted. He's the least intelligent member of his family and the only one to wear glasses.
• Trademark Favorite Food: Pie
• Took a Level in Dumbass: In the movie, he had his dumb moments and wasn't the sharpest tool in the shed, but he mostly resembled a very normal well-meaning father. In the show, he's the quirky ditz we know and love.
• Verbal Tic: He has a tendency to say "dehh" before he begins his sentences.
• Vocal Evolution: His voice originally sounded deeper in the movie before it became goofy and high pitched in the cartoon.

Judy Neutron

Voiced by: Megan Cavanagh

Jimmy's mother. She's happy to cook and clean and run the household, but does want some appreciation for all she does. After all, without her, Jimmy and Hugh's lives fall to pieces.

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• '50s Hair: Lampshaded in "Maternatron Knows Best".
• Action Mom: She's incredibly athletic, coordinated, intelligent, and she keeps a plasma rifle in her utility closet. (For those tough ground-in stains!)
• Adaptational Badass: While she was certainly the more competent parent in the movie, the show substantially expanded her repertoire into an Action Mom.
• Affectionate Nickname: Hugh calls her "Sugarbooger".
• A Day in the Limelight: In "Maternatron Knows Best".
• Deadpan Snarker:
  Judy: Hugh, are you aware that most of the things you say don't make any sense?
  Hugh: I know honey. I know.
• Ditzy Genius: Not ditz per se (she's certainly the intelligent one in her marriage with Hugh and more rational than he is) but she has her moments of ditziness. There are also numerous moments where she demonstrates it's definitely from her side of the gene pool that Jimmy gained his intellect.
• Establishing Character Moment: In the movie, while she first appears to a standard Housewife, she's almost immediately implied to have Hidden Depths when she begins discussing Hugh's car transmission.
• Foolish Husband, Responsible Wife: She's the Responsible Wife to Hugh's Foolish Husband. She's presumed to be where Jimmy got his intellect and tends to be more focused on doing chores. Unlike Hugh, she seems to know how to work Jimmy's inventions.
• Full-Name Ultimatum: "James Isaac Neutron!"
• Good Parents: A loving and nurturing mother towards her son Jimmy.
• Happily Married: To Hugh. In many of their scenes together they're usually shown being lovingly playful with each other and rarely fighting.
• Hypocritical Humor: She says the identical-looking robot mom has a "hideous 1950s hairdo".
• Mama Bear: "Get away from my family, you ugly bucket of bolts!"
• Mundane Utility: Uses a de-molecular cannon beam to clean difficult stains.
• Nice Girl: For the most part, she's a loving mother and wife to her family.
• Only Sane Woman: Along with Libby. She's generally Closer to Earth than Hugh and Jimmy, and takes their quirks in stride... most of the time.
• Stacy's Mom: Carl has a crush on her.
• Women Are Wiser: Compared to her bumbling husband.

Supporting Characters

Bolbi Stroganovsky

Voiced by: Phil LaMarr

A foreign exchange student from the country of Backhairistan, he's a happy-go-lucky, friendly, well-meaning kid who's always there when his friends need him.

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• Breakout Character: Originally introduced as a one-time character but has quickly become a fan favorite. To a point where he seems to be close to another major character.
• Bunny-Ears Lawyer: As silly and strange as he is, he's an excellent actor.
• Butt-Monkey: In "El Magnifico" he pays a slapstick-heavy price so that Mr. Estevez can pull of his superhero hoax in front of Sheen. Not that anyone asked him to.
• Cloudcuckoolander: He makes Sheen look sane by comparison.
• Dance Sensation: The "Slap Dance" from his homeland. "Slap slap slap! Clap clap clap! Slap slap slap! Clap clap clap!"
• The Ditz: Though he seems like just a goofy foreigner at first.
• Funny Foreigner: Kind of like Fez meets Rolf. The difference is that Bolbi's country is actually named (Backhairistan).
• Hidden Depths: He's a very good actor and had Macbeths' Life's But a Walking Shadow monologue committed to memory when he auditioned for the part: Jimmy, Betty, and Nick were left speechless, and Ms. Fowl was reduced to tears.
• Loon with a Heart of Gold: As crazy as he is, he's a good guy who likes to help his friends.
• Ruritania: His homeland of Backhairistan.
• Strong Family Resemblance: His sister is just a slightly shorter version of him in blonde braids and make-up.
• Throw the Dog a Bone: In "Jimmy for President" where he becomes class president after everyone else is disqualified and "Out Darn Spotlight" where he gets the role of villain in the play and does such a good job that Principal Willoughby slates him for a spot in his next production.
• Trademark Favorite Food: Kebabs. They appear to be standard cuisine in his country.
• Took a Level in Badass: In "Win, Lose and Kaboom", he manages to help defeat Meldar's robots.
• Vocal Evolution: Had a slightly deeper voice and heavier accent in his first appearance.

Betty Quinlan

Voiced by: Kath Soucie

The girl of Jimmy's dreams, and sometimes the motivation for hi-jinks in his efforts to impress her. Cindy doesn't care for her... for some reason.

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• Betty and Veronica: Quite literally the sweet-natured Betty to Cindy's Veronica. Ironically, Betty looks like Veronica and Cindy looks like Betty.
• Beware the Nice Ones: Betty is as sweet as a jellybean, but she has her limits (especially when Cindy's jealousy issues are concerned).
• A Day in the Limelight: In "Out Darn Spotlight" and "Vanishing Act".
• Nice Girl: One of the nicest characters, and among the only ones to consistently respect Jimmy.
• Obfuscating Stupidity: She often plays off that she's either oblivious to Jimmy's crush on her or mildly reciprocates it, but "Vanishing Act" reveals that she's fully aware of Cindy's crush on him and supports her, viewing Jimmy as merely a friend.
• The Rival: Unintentionally to Cindy. Had the series continued, there would have been an episode that focused on them. In said episode, Cindy and Betty would've finally opened up to each other and the two would've become friends.
• Satellite Love Interest: Sort of. She's not oblivious to Jimmy's crush on her or Cindy's crush on Jimmy for that matter. It is also implied that while she might be flattered by Jimmy's affections, she knows he belongs with Cindy and is fully supportive of it.
• Shipper on Deck: While she's flattered by Jimmy's crush on her and has shown signs of potentially returning it, she recognizes that he'd be a better match for Cindy and even admits as such in "Vanishing Act".
  Betty: Just relax and keep out of my face. He's all yours.

Ms. Fowl

Voiced by: Andrea Martin

The cast's homeroom teacher.

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• Animal Motifs: Birds. Not just her name, but her appearance and mannerisms (long pointy nose, motioning her arms like wings, squawking, etc.).
  • In "I Dream of Jimmy", in Carl's dream, her desk is replaced by a giant bird nest and she lays eggs.
• Bunny-Ears Lawyer: As odd as she is, she has proven many times to be a Reasonable Authority Figure.
• Cloudcuckoolander: Occasionally teaches subjects that really aren't pertinent to an elementary school education ("And that's why cowboys are bow-legged," anyone?).
  • When all the kids in her class got sick and skipped school, she was so desperate to teach that she started lecturing the empty room and would then sit at the student's desks pretending to be answering her own questions.
• Death Glare: Unlike the other staff members at the school, she doesn't require a weapon to take down the unruly substitute teacher parents in "How To Sink A Sub". She uses her "skunk eye", which immediately intimidates people into backing down.
• Dub Name Change: She is named "Señorita Ave" (Ms. Bird) in the Latin American dub.
• Everyone Has Standards: In a Freeze-Frame Bonus in "My Big Fat Spy Wedding", at Beautiful Gorgeous and Jet Fusion's wedding, she's horrified to see a brainwashed Jet attack and strangle Sheen when Sheen says the trigger phrase.
• Gag Nose: Resembling a beak, taking her whole bird motif much further.
• Hidden Depths: Ms. Fowl isn't just any ordinary teacher.
  • "Foul Bull" — She was once a cowgirl and uses her experience to ultimately save the day.
  • "Lady Sings the News" — Principal Willoughby implies that Miss Fowl might be a trans woman.
  • In the Halloween episode she showed vast knowledge on how to defeat werewolves. As to how she claims she was once married to a werewolf.
• Jerkass to One: While she's normally a fair and reasonable teacher to the rest of her students, she appears to have a particular enmity towards Sheen. Though considering that it's Sheen, you can imagine that there would be some valid reasons for why she considers him her least favorite student.
  Ms. Fowl: I miss them all so much. (cries while inside her empty classroom) Except Sheen!
• Kavorka Man: A female example. She attracted Thomas Edison, went dancing with President Hoover, flirts with Sam and was once married to a werewolf. All this despite being an old woman who looks like a chicken and has similar mannerisms.
• Last-Name Basis: Being a teacher, everyone just calls her Ms. Fowl but in "Substitute Creature" General Ernest Abercrombie states her name is "Winifred".
• Meaningful Name: Fowl is another term for bird, in which fits her Animal Motifs. Her Latin American name, "Señorita Ave", is more literal. (It means Ms. Bird.)
• Noodle Incident: She was once married to a werewolf. She refers to it as "a story for another day". She also apparently served a prison sentence after a "grading and driving" incident, though she rather quickly asserts to Libby that the charges were never proven.
• Reasonable Authority Figure: Despite her eccentricities, she's one of the most sensible adults at the school, especially compared to the more-incompetent Principal Willoughby.
• Stern Teacher: She has her moments.
• Vague Age: Okay, she's old. But how old is she?
  • In one episode, she implies that 58 is young for her.
  • In "Make Room for Daddy-O", she mentions that it is the 82nd annual Father's Day Follies and states that she still remembers the first one like it was yesterday.
  • She's apparently old enough to have taught General Ernest Abercrombie and Dr. Finbarr Calamitous when they were children, the latter of whom is clearly an elderly man.
  • In "How to Sink a Sub", she states she has been teaching for 74 years, which (assuming she started teaching at 18) would make at least 92.
  • Lampshaded in "Attack of the Twonkies".
  Sheen: She is getting on in years, but I'm sure she's not a thousand.
• Verbal Tic: Tends to end sentences with a squawk-like noise.

Principal Willoughby

Voiced by: Rob Paulsen

As the title suggests, the principal of Lindbergh Elementary.

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• The Ditz: Can be rather gullible at times; such as when he bought Sheen's claim of going to the school's "Tanning Salon", hook, line, and sinker. Though it didn't take long for him to realize he'd been duped.
  Willoughby: Wait a minute! We don't have a tanning salon!
• Keet: For a school principal, he is actually rather jovial and eccentric.
• Large Ham: Falls into this territory every now and then.
• Last-Name Basis: Always referred to by his title, though the door to his office reveals his first name: William.
• Putting the "Pal" in Principal: While he's not very good at his job, he's still a friendly and likeable guy who generally gets on well with the students.

Nick Dean

Voiced by: Candi Milo

Another one of Jimmy's friends, who is the cool guy that everybody loves at school, especially the girls.

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• Adaptational Nice Guy: He's much nicer and fleshed out than he was in the movie.
• Adaptational Wimp: In the movie, Jimmy takes the backseat as Nick leads the charge against the Yolkians, and the class Bad Butt even manages to take out a couple of Yolkian guards by hijacking one of their spears... only to lose momentum upon seeing the giant alien-chicken, at which point he becomes completely useless and Jimmy has to lead the charge himself. Nick's later Paper Tiger characterization suggests he would balk at even taking on the guards, if he had to do it again.
• All Girls Want Bad Boys: Which is why all the girls at his school dig him.
• Ambiguously Brown: Nick appears to be Latino or Italian despite his English surname. The creators state that he is Brazilian.
• Attention Whore: He'll do anything for love and attention.
• Bad Butt: Before his later characterization took hold.
• Big Brother Mentor: Nick's like a big brother to Jimmy and often gives him advice to help him out when he's in a jam (even though Jimmy ends up in trouble because of it).
• Big Man on Campus: The coolest guy in Jimmy's class.
• Book Dumb: He never got a 95 in his life.
• Break the Cutie: In "The League of Villains", it is implied he now hates himself.
• The Chew Toy: All of his appearances in Season 3 consist of him breaking his leg while skateboarding. Jimmy lampshades this during one of his news segments in "Lady Sings the News".
• The Charmer: Thanks to his All Girls Want Bad Boys charm.
• Chick Magnet: All the girls find him attractive.
• Deadpan Snarker
  Sheen: Libby's right. We can't give up hope. We need to ask ourselves what Ultra Lord would do.
  Nick: That's actually a good question, Sheen. Maybe he'll just sit on the shelf because he's a doll!
  Sheen: He's not a doll! He's an action figure!
• Demoted to Extra: Nick used to be an important character, but in the last two seasons, he barely shows up at all except to break his leg skateboarding. Had the series continued, Nick would've rejoined the main cast and continued to develop his relationships with Jimmy and the gang.
• Even Bad Men Love Their Mamas: Nick is shown to be a bit of a mama's boy.
• Flanderization: Nick actually did earn his Badbutt credentials in The Movie, successfully stealing a Yolkian laser spear from a guard and then putting both the guard and another nearby through a Curb-Stomp Battle, until he lost his nerve partway through the Yolkian Kaiju hatching. In the show, he mostly became known for the traits of high-pitched screaming and injuring himself.
• Gratuitous German: He sang a lullaby in German to his twonkie, and knowing how twonkies respond to song, it's expected what happened to him.
• Hidden Depths:
  • He only acts like a tough guy because he's insecure and afraid.
  • His operatic German lullaby for his twonkie is carried out in secret.
  • He's actually a very talented actor, as demonstrated in "Out Darn Spotlight" when he nails his audition for the School Play and quickly nabs the lead role.
• Jerk with a Heart of Gold: Nick may be cynical, egotistical, and snarky, but he's also one of Jimmy's best friends and he's actually a really good person.
• Meaningful Name: His last name is a reference to James Dean who is best known for playing similar "bad boy" roles.
• Momma's Boy: He's seen being comforted by his mother during the flight home in The Movie. No dad is present.
• Nice, Mean, and In-Between: He's the Nice to Cindy's Mean and Libby's In-Between. He's the coolest kid in school who's usually nice and easygoing, though he's not without his Beware the Nice Ones moments.
• Noble Male, Roguish Male: The roguish Badbutt to Sheen's Ultra Lord-fanboy noble in the movie.
• Oral Fixation: In the movie, he was often seen with a lollipop in his mouth. Probably intended to be a G-Rated cigarette.
• Paper Tiger: He's the ultimate cool dude, the girls all dig him, and he's supposed to be tough. In the movie, his part of the plan is to take care of the Big Bad while the others rescue their parents. One look at his competition, though, and he goes screaming like a little girl.
• Pretty Boy: Which is why all the girls love him.
• Red Oni, Blue Oni: The blue to Sheen's red.
• Savvy Guy, Energetic Girl: The savvy guy to Brittany's energetic girl.
• Screams Like a Little Girl: Whenever something frightens him, especially once he first saw Poultra's eyes.
• Sensitive Guy and Manly Man: The manly man to Jimmy's sensitive guy.
• Troubled, but Cute: A supposed tough kid who is considered cool and is popular with girls.

Brittany Tenelli

Voiced by: Candi Milo

Cindy's other best friend, who is often seen hanging out with her and Libby as a third member of Cindy's friend circle.

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• Age-Inappropriate Dress: The elementary school sure has a lousy dress code for letting her wear shirts that show off her belly button.
• Ascended Extra: Would've become one in Season 4.
• Cloud Cuckoo Lander: She's a comic foil to the otherwise brainy Cindy and Libby.
• Cute Clumsy Girl: Pretty as she may be, she is kind of a klutz.
• The Ditz: Of Cindy's circle of friends.
• Dumb Blonde: Like a miniature Melody Valentine.
• The Friend Nobody Likes: Cindy and Libby often treat her like this.
• Genius Ditz: She may be doofy, but she's also an awesome dancer.
• Genki Girl: You can hear a lot of Maya Santos in her.
• Girlish Pigtails: She wears her hair in two pigtails, like Cindy did in the movie and shorts.
• Hair of Gold, Heart of Gold: One of the nicest characters in the series.
• Kindhearted Simpleton: She's a ditz, but is the kindest character on the show.
• Nice Girl: One of the few characters who doesn't antagonize Jimmy in any way and she actually seems to admire him.
• Nice, Mean, and In-Between: Whenever she's around, she substitutes for Nick as the Nice to Cindy's Mean and Libby's In-Between.
• No Celebrities Were Harmed: Blonde, hair, valley girl accent, midriff outfits. Sound familiar?
• Savvy Guy, Energetic Girl: The energetic girl to Nick's savvy guy.
• Simpleton Voice: Candi Milo at her best.
• The Sixth Ranger: In Cindy's circle of friends.
• True Companions: With Cindy and Libby.

Butch Pokovski

Voiced by: Rob Paulsen

The school tough on-and-off bully.

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• The Bully: Obviously, given his reputation for punching. But he's nothing compared to even worse bully Terry Finster—and even Butch fears him.
• The Ditz: He possesses ample brawn, but very little brain.
• Eyes Out of Sight: His sleek red hair obscures his eyes.

Sam Melvick

Voiced by: Billy West

Owner of the local hangout joint, The Candy Bar.

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• Bullying a Dragon: Does so in the superhero episode the N-Men. Jimmy is a rampaging orange monster but upon seeing his parents, he starts calming down. Until Sam decides to throw fruit in Hulk/Jimmy's face. Needless to say, the mutated Jimmy doesn't take too kindly to it. This also came up in the Halloween Episode, though he had an angry mob to back him up.
• Deadpan Snarker: One particular instant is in "Krunch Time", when he sarcastically remarks the suspense is killing him when Carl is unable to decide what kind of candy he wants.
• Jerkass: N-Men episode again. He was right that something should have been done to try to help the kids control their newfound powers. However, calling the military up to imprison them and then telling the kid's parents they were just freaks was beyond the pale.
• Jerk with a Heart of Gold: Gold might be stretching it, but he does have softer side for Ms. Fowl.
• Ship Tease: Sometimes has these with Ms. Fowl.
• Ungrateful Bastard: He even says that Jimmy still owes him $1.80 for the heavy seltzer, even after the N-Men thank him for his help.
• Verbal Tic: Has a habit of ending his sentences with, "Yeah!".

Jet Fusion

Voiced by: Christian Slater, Dave Fouquette (videogame)

Jimmy's favorite action movie star, who also happens to be a secret agent in real life.

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• Academic Athlete: Graduated from MIT, CalTech and Hartland, and took extreme sports as part of a school project.
• Anime Hair: Jimmy probably imitates him in this regard.
• Captain Ersatz: A secret agent often depicted wearing a tux. Sound familiar?
• Catchphrase: "Gotta jet!"
• Dating Catwoman: Briefly got engaged to Beautiful Gorgeous, until it was revealed as a plot to kill Jimmy and get him out of the way.
• Distressed Dude:
  • The plot of his debut episode is about Jimmy and his friends having to rescue him from Professor Calamitous.
  • In his second appearance, he's brainwashed by his bride-to-be to assassinate Jimmy in a ploy to get rid of her hated enemies.
• Jerk with a Heart of Gold: A bit of a showoff and full of himself, but a good guy for the most part.
• Perma-Stubble: Always sporting it.

Villains

King Goobot V

Voiced by: Patrick Stewart (movie), S. Scott Bullock (TV series), Joe Whyte (video game)

King of the Yolkians, and Jimmy's first archenemy. In the movie, after making contact with Jimmy's communication satellite, he abducts the adults of Retroville in order to sacrifice them to the Yokian god, Poultra. Ever since Jimmy thwarted this plan, he's been trying to get his revenge on the boy genius.

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• Aliens Are Bastards: An evil monarch from the space.
• Arch-Enemy: To Jimmy.
• Big Bad: The biggest one of the series. He is the main antagonist in the movie and in two episodes. Not to mention the main antagonist in the series' pilot and most recurring villain besides Calamitous.
• Card-Carrying Villain: He proudly claims to be a villain.
• The Chessmaster: In the final episode, he is behind a very well-crafted plan to kill Jimmy.
• Establishing Character Moment: His first scene in the movie has him eating his own pet alien and then having a crew member spaced for unceremoniously showing up in his throne room, all within a minute.
• Even Evil Has Standards: Played for Laughs. In The League of Villains, he disapproves of the Junkman's idea to eat Jimmy, considering it to be disgusting. He also calls Eustace's idea of mounting Jimmy's head on a wall "barbaric".
• Faux Affably Evil: Goobot is funny, hammy and over-the-top, especially when he is in a good mood. However, he is also an authoritative, tyrannical monarch.
• Greater-Scope Villain: Of the PC Jimmy Neutron game.
• Hair-Trigger Temper: He tends to explode with anger when things don't go his way.
• Jerkass: He's arrogant, self-centered, deceiving and authoritative.
• Kick the Dog: He usually does this when he is being outright cruel.
• Laughably Evil: Between his over-the-top reactions and his comical quirks, Goobot is easily one of the funniest villains in the series.
• Legion of Doom: He created "The League of Villains" consisting of several villains from numerous episodes including some of the Rogue Galleries.
• Planet Baron: By all appearances, he's the absolute ruler of every bit of the Yokian's homeworld.
• Psychopathic Manchild: He usually rejoices in his evil deeds, like a cruel child.
• Red Eyes, Take Warning: He has red eyes and is evil.
• Sadist: In "The Eggpire Strikes Back", he is more than excited with the mere idea of destroying Retroville.
• Starter Villain: He was the first villain in the franchise ever since the pilot in fact. Ironically, he was also the Final Boss in The League of Villains.
• Starter Villain Stays: Makes a return in the series including the finale The League of Villains.
• Surrounded by Idiots: Ooblar is nowhere near as intelligent as he is and he only keeps him around because he's his brother. His followers can be like this to some degree, and for that, he punishes them by sucking them out of his spaceship.
• Taught by Experience: Goobot learned from past experiences that Goddard, Jimmy's inventions and friends were things that foiled his plans, so, in The League of Villains, he assigns his comrades to cut down Jimmy's access to them before formally catching him in the series finale.
• Trapped in the Past: What becomes his ultimate fate in the series finale.
• Uncertain Doom: Because both Professor Calamitous and Eustace Strych were seen in the second and third Jimmy/Timmy crossovers, it's unknown if he and the rest of the League of Villains made it back to the present or not.
• Would Hurt a Child: After all the defeats he has received, he is more than willing to kill Jimmy in The League of Villains.

Ooblar

Voiced by: Martin Short (movie), Paul Greenberg (TV series), Mark DeCarlo (video game)

King Goobot's less than competent assistant and brother.

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• Affably Evil: He's unfailingly polite even when he helps Goobot with his wicked whims.
• The Dragon: To Goobot.
• Laughably Evil: Even more than his boss.
• Minion with an F in Evil: Though he does come close to killing Goddard in the movie and mentions that he likes seeing people being spaced.
• Plucky Comic Relief: Serves as a comic relief character whenever he is around.
• Put on a Bus: Goobot apparently traded him for sulfur butter prior to "League of Villains".
• Too Dumb to Live: He's not too bright and this annoyed Goobot so much that, originally, in the novelization, Goobot was supposed to kill him with the Doomstick.

Yolkian Fleet Commander

Voiced by: Rob Paulsen

An important asset of King Goobot's forces and leader of the king's fleet.

---

• Canon Foreigner: He's made for the PC Jimmy Neutron game.
• Creepy Monotone: His voice is full of this.
• Dragon with an Agenda: He is just after Jimmy Neutron, rather than human life compared to his superior.
• Karma Houdini: He let Jimmy and his friends go, without punishment.
• No Name Given: His name is yet to be revealed.
• Red and Black and Evil All Over: His black shell, red eyes and cape signify this.
• Rejected Apology: He rejected his lieutenant's apology for not finding Jimmy before destroying his shell.
• Seeker Archetype: A villainous example, where he longs to find Jimmy Neutron.
• Suddenly Shouting: "Bring me that human boy, NOW!"
• Verbal Tic: "Human boy".
• We Will Meet Again: His last words before he lets Jimmy and his friends leave.
• You Have Failed Me: Said word-for-word after he got angry at his lieutenant.

Poultra

Voiced by: Frank Welker

The Yolkians' "god(ess)", a gigantic chicken monster.

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• Ambiguous Gender: In the film, he's referred to as male and a "god", but in "The Eggpire Strikes Back", she's referred to by female pronouns. This may be justified because the Poultra who appeared in "The Eggpire Strikes Back" wasn't the same one as the original, but the episode words it in a way that suggests that Poultra has always been female.
• Back from the Dead: Subverted - she wasn't killed in the movie, but apparently died in between the movie and the show though Ooblar states she simply left for another civilization. In the TV special "The Eggpire Strikes Back", a duplicate of her is cloned, and Jimmy mentions it's not the same Poultra.
• Feathered Fiend: A giant killer chicken.
• Greater-Scope Villain: While King Goobot is the Big Bad in both the original movie and the episodes that feature him, Poultra is said to be the "god" that the Yolkians look up to.
• Shout-Out: Her second death is a shout-out to the Wawel Dragon, of all things.

Professor Finbarr Calamitous

Voiced by: Tim Curry

Jimmy's other arch-nemesis and the show's main antagonist. A mad scientist with an inability to complete things (though he eventually overcomes this habit). He's constantly hatching evil schemes, usually dragging Jimmy into things.

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• Absent-Minded Professor: Calamitous when introduced was never able to finish anything, even his own sentences. From his second appearance onwards, he can now talk in complete sentences thanks to self-help classes. However, this habit appears again in "The League of Villains".
• Affably Evil: Sure, he's got evil scheme after evil scheme, but he's still a pretty friendly guy. For example, when he suffers a Potty Emergency, he politely asks Sam if he can use the restroom at the Candy Bar, and even tries to order some food when he's told the restrooms are for paying customers only. He even asks Jimmy how his old teacher, Ms. Fowl, is doing.
• Arch-Enemy: Seems to have taken this role up from King Goobot, as he's one of Jimmy's most recurring enemies.
• Beware the Silly Ones: Even before he took self-help classes to help him finish things, he was still as threatening as he was forgetful in his first appearance. He eventually gets to a point where he nearly destroys and remakes an entire universe.
  Jimmy: For a bumbling genius, he's pretty dangerous.
• Big Bad: Expect him to fall into this role a lot, especially during crossovers.
• Ditzy Genius: He's just as smart as Jimmy and capable of building powerful inventions, but incapable of finishing anything he starts.
• Dope Slap: Often gets these from his daughter.
• Evil Counterpart: To Jimmy, although he's much older, and unlike Jimmy he failed elementary school.
• Evil Old Folks: An old man who wants to take over the world with his intellect.
• Fame Through Infamy: In the Nintendo DS version of Nicktoons: Attack of the Toybots, this is Calamitous' ultimate goal with creating the Toybot army, as he was hoping to earn a spot on a reality TV show that would garner him unspeakable infamy for his villainous acts. In the end, Jimmy usurps his spot on the show, and tells Calamitous that he can still earn infamy by making a reality show based on the prison sentence he'll serve for the next 15-to-20 years.
• Fatal Flaw: His inability to finish anything repeatedly comes back to bite him. In his first appearance, he's forced to abandon his pursuit of Jimmy because he kept forgetting to put a bathroom in his robot suit.
• Freudian Excuse: Calamitous was a brilliant student, but he was unable to finish anything and failed Ms. Fowl's class, vowing to come back when the time comes. Through his lifetime, he was ridiculed for this tendency, driving him to seek vengeance.
• In Their Own Image: After being fused with Jorgen von Strangle, he intended to recreate all reality as he saw fit.
• Loophole Abuse: His mini-mecha is basically the only functional piece of equipment he has because he technically never put in a bathroom; everything else he has is usually missing a key component of some sort. It's implied that the whole bathroom bit is how he mentally got over not "completing" it.
• Mad Scientist: He even has the look, the Evil Laugh, and a beautiful daughter.
• Mini-Mecha: A humanoid red model was his best work in his debut. Though it was still technically unfinished since he never put in a bathroom.
• Missing Steps Plan: His big flaw is that he can never finish everything, and while self-help classes help him with his speech problem, this quirk is in full-force in his Evil Plans.
  • In "Operation: Rescue Jet Fusion", his plan is to use his laser to melt the snow off of Mt. Everest, flooding the world so that he can... do something.
  • In "The Great Egg Heist", he tricks Jimmy and his associates to steal a priceless jade egg so that he could power his doomsday device. What he'll do with the device he still hasn't figured out.
• Omnicidal Maniac:
  • In "Operation: Rescue Jet Fusion", he tries to flood Earth to destroy it.
  • In "The Jimmy Timmy Power Hour 2: When Nerds Collide!", he creates a bomb using Jorgen's magic that would have blown up the universe.
  • In Nicktoons Unite!, he and the other villains build a doomsday device powerful enough to destroy universes, with Retroville as the first test. Luckily, he forgot to install a backup supply, meaning he's stopped when the power is cut.
• Speech Impediment: His compulsive inability to finish anything also applies to sentences, usually fishing for the last word. By "Operation: Rescue Jet Fusion", he overcame this problem through a self-help course.
• Take Over the City: In his first appearance. Jimmy assumes he's just gonna Take Over the World, but he says he's going for something smaller.
• Unrobotic Reveal: In his debut episode, Calamitous was shown piloting his mini-mecha, which he soon exits, revealing himself to be a human.
• Would Hurt a Child: Considering the showdown he usually has with Jimmy, this trope suits him. In a crossover with The Fairly OddParents!, he outright tried to kill him using Jorgen's magic. Thankfully, fairy magic is not made to harm.

Beautiful Gorgeous

Voiced by: Wendie Malick

Professor Calamitous' daughter. Her real name's Georgia Calamitous. Jimmy, Carl, and Sheen are easily seduced by her looks.

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• Affably Evil: Much like her dad. In her very first appearance, she chats amiably with Jimmy, Carl and Sheen and even serves them milkshakes before almost regretfully saying she'll have to kill them.
• Annoying Laugh: Snorting variation in every full, uninterrupted Evil Laugh. Sheen even lampshades it.
• Beleaguered Assistant: In Operation: Jet Fusion. She often bemoans having to do Calamitous' dirty work and put up with his eccentricities.
• Bond Villain Stupidity: She devised a death trap for Jimmy and Jet Fusion instead of killing them directly like the majority of Bond villains. Considering her debut is in an episode parodying spy films, it's to be expected.
• Career Not Taken: A Running Gag has her almost admitting what she really wanted to do (revealed in "My Big Fat Spy Wedding" being putting aglets onto the ends of shoelaces), but her father Dr. Calamitous raised her to be a supervillain just like him.
• Characterization Marches On: Her first appearance implies that she was only evil reluctantly, feeling obligated to engage in it out of loyalty to her father. This doesn't carry over to later episodes.
• Dark Action Girl: She's a very skilled martial artist and nearly defeats Jet Fusion in hand-to-hand combat.
• Deadpan Snarker: She often has something snarky to say.
• Dude Magnet: How every guy in the show reacts towards her.
• I Know Karate: To be accurate, she knows 112 forms of martial arts. She proved her prowess by getting the upper hand on Jet Fusion.
• Impossible Hourglass Figure: Her waist is comically small, and her bust is much larger than any other character in the show
• Interspecies Romance: With the Junkman due to Jimmy's Love Potion.
• Mad Scientist's Beautiful Daughter: Her name is half James Bond Reference, half beating this trope over your head.
• Meaningful Name: She wasn't exactly very creative with the villain alias. Or subtle.
• Mind-Control Device: She made one to hypnotize Jet Fusion in the form of a box of candy. Also did this Jimmy with his Hypno Ray.
• Ms. Fanservice: Understatement of the year.
• Older Than They Look: Jimmy guessed 22, which based on her amused face, isn't accurate. Still Beautiful seemed quite flattered he'd mistakenly think that.
• Proud Beauty: Her self given villain name says everything.
• Running Gag: Every time she mentions she wanted to have a certain career other then villainy, she always gets interrupted or cut off. It was to make aglets for a living.
• Sensual Spandex: Usually seen wearing a form fitting black catsuit.
• The Tease: Enjoys the effect her sex appeal has on men, often playing it up to toy with them. Perfectly demonstrated by Jimmy, Sheen and Carl's reactions to her during their first encounter, Gorgeous clearly getting a kick out of how flustered she makes them.
• Then Let Me Be Evil: Apparently she never wanted to be evil; just felt obligated to because her father was doing it. Then comes "My Big Fat Spy Wedding"...
• Trapped in the Past: Which becomes her fate at the end of the series.
• Ugly Guy, Hot Wife: With Junkman.
• The Ugly Guy's Hot Daughter: Her dad's very short and peculiar-looking at best, while she very much lives up to her name. Presumably, she got her looks from her mother.
• Uncertain Doom: Because both her father Professor Calamitous and Eustace Strych were seen in the second and third Jimmy/Timmy crossovers, it's unknown if Gorgeous and the rest of the League of Villains made it back to the present or not.

Eustace Strych

Voiced by: Rob Paulsen

A snobby rich kid who buys all of his gadgets from his dad. He's one of the members of the League of Villains created by Goobot.

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• Arch-Enemy: He sees Jimmy as one. Along with King Goobot and Calamitous, he's one of the most recurring villains in the show.
• Ax-Crazy: He's very good at hiding it. He laughs maniacally in "King of Mars"; and in "The League of Villains", he expressed the desire to hang Jimmy's head on the wall, something that even Goobot considered it "barbaric".
• Bad Boss: He uses his personal butler, Blix as an abuse dummy.
• British Teeth: Unlike most examples of this trope, he doesn't have crooked or yellow teeth. He does however have large buck teeth that stick out. Jimmy even calls him "Captain Overbite" in his debut episode.
• The Charmer: The main reason why Cindy had a crush on him.
• Comedic Sociopath: Perhaps Eustace really qualifies as a true sociopath. Nevertheless, his butler, Blix is often used as an "abuse dummy" for his rage or to add to him being hilarious.
• Evil Brit: Has a British Accent to go with his rich jerk persona.
• Evil Counterpart:
  • To Jimmy. They both have a lot of high-tech gadgets, but while Jimmy is usually well-behaved and makes them himself, Eustace has his inventions bought and is a spoiled brat.
  • Unintentional, but his status as the cool guy and The Charmer makes him an evil version of Nick Dean.
• Evil Is Petty: He's a petty, sadistic jerk.
• Expospeak Gag: He toasts Jimmy a flowery, grandiloquent way, knowing Jimmy wouldn't understand and assume he was being insulted. In reality, Eustace was complimenting him, just sarcastically.
• Faux Affably Evil: When he's in a good mood, Eustace is fairly polite and charming. Underneath his polite facade, however, he's unpleasantly malicious and petty.
• Hate Sink: He is incredibly arrogant, vain, narcissistic, snobby, and while he is not as evil as most of the show's villains, he compensates by being an incredibly irritating Smug Snake without redeeming qualities. Just think of Princess Morbucks as a male version.
• Jerkass: He's cruel, obnoxious, and used Cindy's love to emotionally crush Jimmy and then, he forced Jimmy to watch Goddard die.
• Jerk with a Heart of Jerk: He showered Jimmy's friends with gifts and a banquet, but it was all just to make Jimmy jealous.
• Kick the Dog: He does many in his first appearance:
  • First, he steals Jimmy's friends with gifts.
  • Second, he says mean things to Jimmy in front of his friends and Hugh.
  • Finally, he makes Jimmy bet Goddard in a battle against his robot cat and when he reveals his true colors, he throws Cindy to the ground and insults her.
• Laughably Evil: He may be an obnoxious asshole, but he can be hilarious at times.
• Literal Ass-Kicking: In "Billion Dollar Boy", he angrily kicks his butler in the butt when he loses two competitions to Jimmy.
• Manipulative Bastard: Both in "Billion Dollar Boy" and "King of Mars", he manipulated Cindy with his superficial charm.
• Polite Villains, Rude Heroes: When he is in a good mood, Eustace is polite, superficially charming, has stereotypical mannerisms of the highest social status, and speaks in a formal manner; while Jimmy, The Hero, is a blunt, rude boy with No Social Skills.
• Pragmatic Villainy: Forms an Enemy Mine with Jimmy and his pals in "King of Mars" when the Martians try to destroy it. Not because of any moral reasons, mind you, but because Earth is where he keeps all his stuff.
• Rich Bastard: While his billionaire dad is a decent guy, Eustace himself is a selfish, ruthless jerk.
• Sissy Villain: During The League of Villains, he possesses weirdly effeminate mannerisms.
• The Sociopath: He's manipulative, uncaring, abusive, unapologetic, narcissistic, and overall cruel to everyone around him without even a shred of remorse. He even suggested mounting Jimmy's head on a pike.
• Smug Snake: Probably one of the less threatening antagonists Jimmy has faced.
• Soft-Spoken Sadist: When he is calm, he doesn't raise his voice.
• Sore Loser: Whenever he loses a competition, he has Blix bend down while he kicks him in the rear repeatedly.
• Spoiled Brat: His father has difficulty disciplining him until Hugh encourages him to do so. When his dad finally punishes him for his misbehavior, he just yells at him while crying when he's sent to his room.
• Tantrum Throwing: Done when he's kicking his butler.
• Trapped in the Past: His fate in the series finale, though he was seen back in the present time in the third Jimmy/Timmy crossover.

Jimmy Negatron

Voiced by: Debi Derryberry

An evil boy genius who lives in the Evil Dimension.

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• Beard of Evil: Despite being a preteen, he has a beard-which is a Shout-Out to Evil!Spock from Star Trek: The Original Series.
• Big Bad: Of "Jimmy Neutron vs. Jimmy Negatron".
• Canon Foreigner: Made for the Jimmy Neutron vs. Jimmy Negatron game.
• Canon Immigrant: Downplayed. His traits served as the inspiration for fellow villain Evil Jimmy.
• Evil Genius: A self-described "evil boy genius".
• Evil Twin: Of Jimmy Neutron, he uses his inventions to torment and conquer.
• Faux Affably Evil: He acts amiable towards Jimmy at first, but it doesn't change the fact that he's unrepentantly evil.
• For the Evulz: He is an EVIL Boy Genius.
• Mecha-Mooks: He has inventions of other types, but robot minions seem to be his specialty.
• Underwater Base: His headquarters back in his home dimension.

The Herminator

Voiced by: Rob Paulsen

A creation of Jimmy Negatron who can travel through time.

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• The Ahnold: Thanks to the fact he is a spoof of the Terminator.
• Canon Foreigner: Made for the Jimmy Neutron vs. Jimmy Negatron game.
• Cool Shades: In a loading screen for the game, he is seen wearing them.
• The Dragon: For Negatron.
• Expy: Of the T-800 from The Terminator.
• Foil: To Goddard. Both are robots made by their respective creators.
• Heel–Face Turn: He redeems himself, albeit unintentionally, to imprison Negatron when he thinks he's Neutron trying to trick him again.
• In-Universe Nickname: Hermin.
• Locked in a Room: Hermin likes to get locked up in the broom closet.
• Minion with an F in Evil: Hermin isn't bright for an evil creation.
• SkeleBot 9000: He is a robotic skeleton.

The Nanobots

Voiced by: Daran Norris (01) and Tom Kenny (02)

A duo of nanobots created by Jimmy to operate several of his inventions. They almost immediately go haywire and become increasingly insane and fanatical as the series goes on.

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• A.I. Is a Crapshoot: They're designed to balance each other out, but they mostly seem to do the opposite. They're constantly bickering with each other, and when they do agree, it's to make extreme misinterpretations of Jimmy's demands.
• Beware the Silly Ones: Their personalities and bickering are mostly comical. However, these two are easily among the most dangerous antagonists in the series as their second appearance saw them literally seconds away from the extinction of the human race.
• Cutting the Knot: In their second appearance, this is how they resolve Jimmy's first attempt to beat them. Jimmy argues that humans are naturally flawed, and that such flaws are natural and a sign that humans are working perfectly. After some pondering, the nanobots file the conundrum and humanity as an extreme error. Since they're meant to delete extreme errors, they decide to delete everyone.
• Cyber Cyclops: They were originally built with one eye in their debut appearance, but Jimmy later upgraded them with two eyes after that.
• Fat and Skinny: 01 is shorter and rounder while 02 is tall and lanky.
• Knight Templar: They take their anti-bullying directive (and whatever other task Jimmy gives them) VERY seriously and well beyond the point of overkill.
• Logic Bomb: How they are typically defeated. Their first appearance Jimmy abused their directive to protect him from attackers by beating himself up in front of them. In their second appearance (after Jimmy's first attempt at this made things much, MUCH worse) Jimmy overloaded them by forcing them to calculate the exact value of pi. In addition, when Jimmy repurposes them to proofread his artistic classwork, his attempts at poetry are so bad they also has this effect.
• Obliviously Evil: To them, they're not doing anything wrong. They're simply carrying out Jimmy's orders to protect him/correct errors. And in Fundemonium, they're convinced that the townsfolk they are terrorizing are enjoying the mayhem they cause.
  01: It warms my dials to bring such joy to the world.
  02: (sighs happily) I too feel the love. KEEP FIRING!

Meldar Prime

Voiced by: Tim Allen, Jess Harnell (singing voice)

The host of the hit game show "Intergalactic Showdown" and the main villain of the TV movie "Win Lose and Kaboom".

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• Aliens Are Bastards: He's an alien and an Omnicidal Maniac.
• Big Bad: Of "Win Lose And Kaboom".
• Deadpan Snarker: Quite a bit.
  (after Sheen gets torched by an alien) Oh nice try Sparky, but next time wait till I START THE GAME.
• Faux Affably Evil: Rarely drops his cheery, hammy attitude even while threatening to blow up people's planets. At the end, he finally stops and decides to get serious.
• For the Evulz: He threatens to destroy other people's planets. Why? To get better ratings.
• Hypocrite: Insists during the race that there's no cheating allowed, but permits the Brains to put Jimmy and the gang into a Lotus-Eater Machine. Later he panics at the idea of his quadrant being blown up despite the fact that his entire show is about blowing up completely innocent planets simply because their species lost a game.
• Large Ham: He's a Game Show host. It comes with the territory.
• Laser-Guided Karma: He is forced to hand over his show to the Brain aliens and advertise an exercise machine that implements Electric Torture, which he says is extremely painful.
• Laughably Evil: Despite being an evil alien, he's very funny and over-the-top.
• Mundane Utility: He has a pair of "matrix generators" with a seemingly limitless ability to manipulate time and space. How does he use them? To create a high-stakes game show, of course.
• Omnicidal Maniac: "Winner gets a brand new car! Loser gets their home planet destroyed!"
• Reality Warper: Thanks to the matrix generators in his cufflinks.
• Smug Snake: He's definitely dangerous, but his pride makes him rather short-sighted.
• Sufficiently Advanced Alien: His seemingly supernatural hold over reality, time and space is powered by a pair of matrix generators hidden in his cufflinks.
• Time Abyss: Implied, as April states that his show has existed for eons.
• Vile Villain, Saccharine Show: He is more than capable of destroying planets and transmitting matter and energy, courtesy of his matrix generators.
• Villainous Breakdown: Loses it when he discovers that his show is about to be destroyed.

Zix, Travoltron, and Tee

L-R: Tee, Travoltron, Zix

Voiced by: Maurice LaMarche (Zix), Jeff Bennett (Travoltron), Kevin Michael Richardson (Tee)

A trio of space bandits Jimmy and friends met when they tried to dig for Asterubies. Later, they tried to sell shrunken Retroville townspeople as toys and joined the League of Villains.

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• Aborted Arc: After taking the melted McSpanky's building as their vessel, Zix states that they'll go hunt down the "captain" Skeet. But this never went anywhere unless they found him offscreen.
• Actor Allusion: Tee isn't Kevin Michael Richardson's first role being a Mr. T Expy.
• Armor-Piercing Question: After having a Heel–Face Turn of his own, Tee uses one of these on Zix and Travoltron to make them undergo one.
  Tee: Well why ya gotta be villains?!
  (Both Zix and Travoltron stammer trying to find an answer and failing)
• Butt-Monkey: Tee was treated as this by his fellows in the League of Villains. This and Sheen's willingness to hear his story out were what triggered his Heel–Face Turn.
• Finger Gun: All three of them use this motion when shooting some kind of gooey substance used in sealing Jimmy's lab.
• Good Feels Good: What Zix and Travoltron thought after helping Jimmy and friends, showing that their Heel–Face Turn would be permanent.
• Heel–Face Turn: Tee during Jimmy and Sheen's imprisonment. Zix and Travoltron followed during the cast's time in the Cretaceous Era.
• Man Hug: Tee really likes to give this. Well, a bit too much. Travoltron too, to a lesser extent.
• Mistaken for Gay: While his orientation isn't known, Zix & Travoltron have this reaction to Tee wanting to open up a dress shop as they glance at one another awkwardly & slowly back away from him.
• Mistreatment-Induced Betrayal: Tee turns against the League of Villains because most of its other members continuously demean and disrespect him.
• Nice, Mean, and In-Between: Travoltron, Tee, and Zix, respectively. Travoltron is the Nice, who like Sheen, is the wackiest of the trio and is often smiling. Tee is the Mean, being the most confrontational and aggressive of the group. Zix is the In-Between who is the often level-headed leader that tries to keep the trio together, while at the same time, trying to accomplish their evil goal at the time. Once they all pull a Heel–Face Turn at the end of the series, they all become nice.
• No Celebrities Were Harmed:
  • Tee is an alien who talks and acts like Mr. T.
  • Travoltron was derived from and acts like John Travolta. Or at least his character in Saturday Night Fever.
  • The third one, Zix, talks like Jon Lovitz. A bit more devious than Jon Lovitz though...
• Real Men Hate Affection: In contrary to Tee and Travoltron, Zix hates the Man Hug, but he will accept a handshake with his teammates.
• Real Men Wear Pink: Tee mentions in "The Incredible Shrinking Town" that he dreams of opening a dress shop.
• Speaks Fluent Animal: Since their species is apparently reptilian, they can understand and speak lizards' language. They use this ability to distract a T-rex from eating Jimmy and his friends.
• Thin Chin of Sin: All three of them have a distinctively pointed chin. When their faces are neutral, their jaws resemble bandanas, which is fitting for a trio of bandits.
• Verbal Tic: Tee tends to have "Fool!" in most of his sentences.

The Twonkies

Sheen's Twonkie

Voiced by: Rob Paulsen

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• Berserk Button: MUSIC. Particularly pleasant music as they consider awful singing to be lullabies for them. Although this seems to have stopped after their first appearance, though, as one can be seen during a big musical number at one point.
• The Cameo: They can be seen appearing in a brief time in several episodes, can even be seen several times in one episode.
• Expy: They're very reminiscent of the titular monsters from Gremlins (starting out as harmless and cute creatures before morphing into dangerous monsters) as well as the Crites from Critters (they're aliens and they often get around by rolling into balls).
• Fish Eyes: They have them.
• Killer Rabbit: And how?
  • Villain Decay: After their first appearance, Twonkies are treated as if they were normal rabbits.
• Monster of the Week: In Attack of the Twonkies. They later became Recurring Extras.
• Only One Finds It Fun: The twonkies respond positively to Sheen's Hollywood Tone-Deaf singing. Jimmy uses this to pacify the transformed twonkies and send them back to space.

The Junkman

Voiced by: Charlie Adler

An alien. He runs a shady trash-collecting business.

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• Catchphrase: "You trash it, I cash it!"
• Dirty Coward: He breaks his promise to Jimmy, Carl, Sheen, Goddard and the Brobot's and leaves them on the ship to die.
• Even Bad Men Love Their Mamas: Subverted. He sold his mother and took the best offer for her due to the fact that he "couldn't put a price on her".
• Extra Eyes: Has an additional set of eyes on the back of his head.
• Fat Bastard: He's a fat jerk who only cares about the profits that can be made from what he can sell.
• Faux Affably Evil: Surprisingly laid back for a repulsive alien creature that runs a shady business, but at his core is positively ruthless.
• Interspecies Romance: With Beautiful Gorgeous.
• Large Ham: A Charlie Adler speciality.
• Multi-Armed and Dangerous: He has four arms and is really evil.
• Pet the Dog: Subverted; He mentions that his alien dog, Roxie, is the only thing in the galaxy that ever showed him love, loyalty and affection...then offers to sell her for a ludicrously high price. He's also not pleased when she falls in love with Goddard and calls her a traitor.
• Trapped in the Past: His fate in the series finale.
• Uncertain Doom: Because both Professor Calamitous and Eustace Strych were seen in the second and third Jimmy/Timmy crossovers, it's unknown if he and the rest of the League of Villans made it back to the present or not.
• Unholy Matrimony: Parodied when Jimmy uses a love potion on him and Beautiful Gorgeous. Their hatred for each other promptly becomes love.

Baby Eddie

Voiced by: Mark DeCarlo

Jimmy's 17.5-month-old cousin. Despite his infantile appearance, he's actually very devious and a genius; capable of walking, speaking fluently, and devising a plan to kill all of the Neutron family members. He later joined Goobot's League of Villains.

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• Always Someone Better: He's even smarter than Jimmy, even as a baby.
• Ax-Crazy: He is incredibly sadistic, murderous and violent.
• Beneath Suspicion: Jimmy was able to deduce that one member of his extended family was secretly a genius capable of sabotaging his invention. Unfortunately, he never suspected that the secret genius was a toddler, and Eddie only reveals himself when he gets the upper hand.
• Bitch in Sheep's Clothing: His first appearance. Since his identity had been uncovered, he dropped the nice facade in subsequent appearances.
• Brainy Baby: A baby capable of reading, walking, talking and various things human adults can do, except changing his own diapers and controlling his excretion/digestive system.
• Casanova Wannabe: Tried flirting with Beautiful Gorgeous, with negative results.
• Charlie Brown Baldness: Has one visible gravity-defying strand of hair only. Justified, in that he's still a baby.
• Cool Bike: His motorcycle can frickin' bring him to space. Too bad it only appeared in the "bad guys assemble montage" at the beginning of the "League of Villains" episode.
• Enfant Terrible: Duh.
• Evil Genius: Who knows how a 17.5-month-old baby can outsmart Jimmy at first, and almost succeed in killing his family members using Jimmy's own things?
• Evil Sounds Deep: He has a really deep voice, a clear contrast to his small appearance.
• In the Blood: In earlier seasons, it was implied that Jimmy gets his smarts from his mother, but Eddie's debut episode reveals that there's a recessive gene on Hugh's side that occasionally sires a super-genius. Jimmy's got it, and so does Eddie.
• Likes Older Women: He has a thing for Beautiful Gorgeous, who's at least 20 years his senior. Of course, being an infant means most women are older than him by default.
• Only Sane Man: Putting aside his need to change diapers, he's mostly this with King Goobot.
• Reused Character Design: His model was reused from when Granny Neutron turned into a baby in "Granny Baby".
• Running Gag: He kept asking his fellow teammates to change his diaper with no success. The joke came in full circle when he took off his own 5-day-old diaper to chase a T-Rex away.
• Stating the Simple Solution: While other members of the League of Villains debated on how to kill Jimmy and Sheen using convoluted (or even silly) ways, he stepped up and said "Just blow him into deep space!" to which everyone agreed.
• Time Out: Jimmy's Aunt Amanda gives him one at the end of the episode "Clash of The Cousins" after he attempted to fake his innocence and anger her.
• Trapped in the Past: His official defeat.
• Uncertain Doom: Because both Professor Calamitous and Eustace Strych were seen in the second and third Jimmy/Timmy crossovers, it's unknown if he and the rest of the League of Villains made it back to the present or not.
• Vocal Dissonance: Despite being an infant, he has a pretty deep voice.
• Wounded Gazelle Gambit: In the episode "Clash of The Cousins". He was only able to keep up this facade for so long though before Aunt Amanda became furious at the fact that she had been defending his actions and soon forgives Jimmy while giving Baby Eddie a timeout.

Grandma Taters

Voiced by: Edie McClurg

An alien who looks like an old lady. She attempted to hypnotize the world into a state of perpetual happiness with her TV Program "The Happy Show Show", but was foiled by Jimmy and Cindy. She later joins the League of Villains to take revenge on Jimmy.

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• Ambiguously Evil: What she's up to is unambiguously creepy and sinister, but it's unclear if she herself had altruistic motives or had some hidden, evil purpose. In her second appearance, she's clearly evil, motivated solely by revenge on Jimmy.
• Affably Evil: One of the best examples in the show. She has a friendly, pleasant and sugary-sweet demeanor, despite being an evil alien being that wants to hypnotize all of humanity.
• Black Eyes of Evil: Can make her eyes look like this at will.
• Getting Smilies Painted on Your Soul: Her show does this, hypnotizing anyone who watches it through to the end into being constantly happy.
• Graceful Loser: Takes both of her defeats in stride. Fitting, considering her Affably Evil status.
• Granny Classic: Played around with. Grandma Taters is genuinely as polite and sweet as she presents herself as being, but she's also an evil alien invader.
• Human Aliens: Her entire species apparently looks like a bunch of identical old ladies. They also all have the same Affably Evil demeanor.
• Mass Hypnosis: Her debut episode, she uses a TV series to hypnotize the whole world into becoming Stepford Smilers.
• Team Mom: Surprisingly (or maybe not so surprisingly), she acts rather motherly towards the other members of the League of Villains, including consoling Professor Calamitous when Beautiful Gorgeous falls in love with the Junkman. Though she draws the line at changing Eddie's diaper.
• To Serve Man: She apparently likes to drink brain juice and in "League of Villains" she tells Baby Eddie that she could literally "eat him up" if she wanted to.
• Trapped in the Past: With the other villains.
• Uncertain Doom: Because both Professor Calamitous and Eustace Strych were seen in the second and third Jimmy/Timmy crossovers, it's unknown if she and the rest of the League of Villains made it back to the present or not.
• Well-Intentioned Extremist: Seems to see herself as one, at least, as she claims that she genuinely wanted to make everyone happy. Her way of going about it wasn't pleasant, though.

Dr. Sidney Moist

Voiced by: Jeff Bennett

A very, very eccentric scientist stationed in the mysterious Bahama Quadrangle, where he's responsible for the disappearances there, turning people into "algae men".

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• Affably Evil: Fairly polite for a crazy lunatic.
• Cloudcuckoolander: He really puts the "mad" in "mad scientist". His affinity for tap dancing is just the first clue.
• Large Ham: He's VERY dramatic.
• Laughably Evil: It's hard to take him seriously when he's dancing around and shouting every other scene.
• Mad Scientist: He kidnaps people and turns them into plant people to act as his personal servants.

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