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James "Jimmy" Isaac Neutron
Voiced by: Debi DerryberryThe main protagonist. He is a boy with a stunning IQ 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?
- Adorkable: He's a nerdy protagonist.
- 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.
- Anime Hair: Lampshaded consistently.
- 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. That being said...:
- In "See Jimmy Run" he comes up with a pair of super-fast shoes in order to beat Cindy at a relay race. When his efforts fail, he resorts to take revenge on her by putting her in all sorts of misfortune. In other words, Jimmy punishes Cindy for being better than him at something. He does get his comeuppance at the end though.
- It's not exactly uncommon in the show to see similar scenarios play out but the big difference is that here we never see Jimmy actually learning from his mistake.
- "Love Potion 976/J" features Jimmy falling for Cindy as a result of being accidentally exposed to the titular love potion and he invites her over to his lab to ask her to be his Valentine. He does snap out of it once he realizes what happened and promptly tosses Cindy out of the lab. Considering that we know for a fact that Jimmy does indeed have a crush on Cindy anyway (although he himself doesn't seem to quite realize that until the very few last episodes of the show, as opposed to her who secretly loves him from the start but just won't admit it), he gives her quite a rough treatment (at one point even calling her gross) and we may assume that for all Cindy knew, he was just playing a mean joke on her.
- In "See Jimmy Run" he comes up with a pair of super-fast shoes in order to beat Cindy at a relay race. When his efforts fail, he resorts to take revenge on her by putting her in all sorts of misfortune. In other words, Jimmy punishes Cindy for being better than him at something. He does get his comeuppance at the end though.
- Belligerent Sexual Tension: With Cindy.
- Berserk Button: Do NOT give Jimmy an F. Denzel Crocker in the Jimmy Timmy Power Hour learns this the hard way.
- Beware the Nice Ones: While Jimmy's hardly a stoic, it takes a lot of effort for his close friends to really piss him off.
- In "Carl Wheezer: Boy Genius", in which Carl's taking on Jimmy's genius identity just to impress a girl pushes Jimmy to the absolute limits of sanity. Considering that Carl is more than willing to abuse his lowly assistant, nobody can blame Jimmy for wanting to blow his friend's cover at any given time and for punching him in the face.
- In "The N-Men", where he gets turned into a big jerk monster after years of putting up with Cindy and her insults. It is also only when Cindy sees the army about to kill him, that she realizes this is all her fault.
- Big Damn Heroes: ALL THE TIME. Often Lampshaded, in fact.
- Big "NO!": Whenever Jimmy comes to any shocking realization, you can bet the whole of Retroville will know about it instantenously.
- 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 comments 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 doneJimmy: *jumping and pumping fist to the air* "I did it! She likes me! She's gonna go out with me! I made a date with Cindy!" *beat* "NOOOOOOOOOOOOOOOOOO!" *shot of him from up, and then zooms out to Retroville and Earth*
- Black Sheep: In one episode, 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. Luckily at the end, they realize Jimmy saved the entire Neutron clan and learn to appreciate him.
- 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: Happens whenever something really bad happens to someone he deeply cares about. Especially Goddard.
- Breakout Character: During the time of the film and the early run of the series, Jimmy became the mascot for Nickelodeon.
- 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 troubles. 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 Poultra is bearing down on him.
- Catch Phrase: 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.)
- Child Prodigy: A teenage boy genius who has an impossible IQ of 210.
- Cheaters Never Prosper: 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.
- 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.
- Deadpan Snarker:Jimmy: *science babble about a spider*Sheen: Fascinating! Can you make it do the hokey pokey?Jimmy: Sheen, go home.
- Expy: He's very similar to Dexter, being a diminiuitive and easily frustrated boy genius who has his own laboratory which leads to hillarious mishaps. Ones wonders what it would have been like if he had to deal with Dee Dee.
- Fatal Flaw: Jimmy's greatest flaws are a combo of Pride and his lack of common sense; in fact, many of the conflicts in the show are born out of this.
- Flanderization: In the movie, he was more awkward, childlike, naive, clumsy and shy. In the series, he's the arrogant, well-meaning, show-offy, know-it-all genius we know and love. Basically he was Jacob Two-Two is he was a boy genius.
- The Friend Nobody Likes: In a small way. His brains and brilliance (and him endangering the town) make him unpopular with the other kids.
- Future Loser: In the 'Bad Future' of The Tomorrow Boys, Future!Jimmy is a slack-jawed loser, wanted by the evil dictator Libby, with a five-o'clock shadow and Cindy as a wife. Current!Jimmy is less than impressed.
- Gadgeteer Genius: He is only a kid, but he has already surpassed any known scientist in capablity. Each episode focuses on one of his invention 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.
- He Cleans Up Nicely:
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."
- 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.
- 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.
- Idiot Hero: For a genius, Jimmy sure makes a lot of utterly stupid decisions. In fact, most of the conflict that goes on in this show is the result of Jimmy making a questionable judgment call in the first place regarding his experiments. But then again, Jimmy's lack of common sense is arguably one of the main points of the series. He may be a "genius," but he's still a child.
- 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?"
- Insufferable Genius: At times, but often more pronounced when Cindy's around. He tries not to be.
- Intelligence Equals Isolation: Sometimes intelligence isolates him, often he sets the (horrible) events of the plot in motion causing him to be isolated, sometimes the characters realize they need his intellect &/or like him more than they let on, and sometimes he's just an insufferable genius. He actually purposely made himself stupid in one episode to end his misery, but the machines accidentally set his intelligence so low he became a complete moron.
- Kid Hero: Jimmy is only 12.
- Little Professor Dialogue: Justified partially in that he does actually have an IQ of 210.
- Nerds Are Innocent: He's a child prodigy who loves and excels at science...and still believes in cooties.
- 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. However, this trope is used less and less in later episodes.
- 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.
- Properly Paranoid: He knew better than to trust the Yolkians in "The Eggpire Strikes Back."
- Puppy Love: With Cindy.
- 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.
- Rival Turned Evil: In The N-Men...
- Science Hero: He embodies this trope for kids shows, along with Dexter.
- Sesquipedalian Loquaciousness: A frequent user and abuser.
- Slap-Slap-Kiss: With Cindy. All the time.
- Teens Are Short: Well, Jimmy at least. Though sometimes he appears to be the same height as some of his friends, possibly an animation error.
- The Smart Guy: Obviously.
- Took a Level in Dumbass: For someone so smart he tends to let his overconfidence and arrogance get the best of him quite a few times. When he accidentally drained his brain too much in Normal Boy.
- TV Genius: He is an elementary school student 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.
- 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 Adorkable personality. Now it's more deep and clear.
- Yank the Dog's Chain: One of Jimmy's signature flaws. When some of his inventions start off good, then backfire on him right afterwards.
Carlton "Carl" Ulysses Wheezer
Voiced by: Rob PaulsenJimmy's shy, asthmatic best friend who has an unhealthy obsession with llamas and Jimmy's mom.
- 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:Carl: I don't eat newspapers! (Beat) Well, I'm trying to quit.
- Butt Monkey: He's the Guinea pig to all of Jimmy's experiments.
- Cowardly Sidekick: To Jimmy.
- Catch Phrase: "My scapula..."
- 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.
- 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: Implied quite heavily 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 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. Then Carl starts milking the moment by berating and constantly screaming at him for all his mistakes. Even by the end, when Jimmy has saved his life at least three times, Carl is still screaming at him... and projecting his own insecurities onto Jimmy to boot. Finally, Jimmy gets fed up with Carl's ungratefulness and punches him in the face.
- Likes Older Women: Carl has a crush on Jimmy's mom since Love Potion #976-J. He's also attracted to the class's teacher, Miss Fowl, who's in her fifties. At least.
- 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.
- Nerds Are Innocent: He's a nerdy boy who's shy, sensitive, and often serves (or at least tries to) as the moral compass in his group of friends.
- Nerdy Inhaler: Carl uses an inhaler very frequently and is also allergic to almost everything.
- Ow, My Body Part!: A weirdly specific example—he seems to have a really tender scapula.
- Precocious Crush: On Jimmy's mom.
- Shrinking Violet: He's generally shy and nervous.
- Sickly Neurotic Geek: What else can you expect with a surname like 'Wheezer'?
- Stalker with a Crush: To Jimmy's mom.
- Voice Changeling: In The Incredible Shrinking Town, It was said he coould do this from a ventriloquism lesson. The result was awesome. He was capable of impersonating Cindy's Mom's and Zix's voice perfectly.
- Youthful Freckles: Has many freckles that match his red hair.
Sheen Juarrera Estevez
Voiced by: Jeffrey GarciaJimmy's hyperactive other best friend who is obsessed with the comic book superhero Ultra Lord.
- 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".
- 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.
- 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 Yoo-Yee to get her back.
- Breakout Character: Gets his own Spin-Off, Planet Sheen. That doesn't mean people liked it.
- 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.
- 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.
- The Ditz: His IQ is 32.
- Drunk with Power: When his intelligence is increased in Sheen's Brain.
- Early Installment Weirdness: He mentions a sister in "I Dream of Jimmy" but Word of God has said since to disregard it. Canonically, Sheen is an only child who lives with his father and grandmother (at least until Planet Sheen).
- Extraverted Nerd: An eccentric comic book-loving nerd.
- Flanderization: In Planet Sheen, all of his serious traits are totally erased; changing him from his nerdy and hyperactive self to an obnoxious prick.
- The Friend Nobody Likes: While his friends do care about him, he constantly annoys them with his ramblings about Ultra Lord, low intelligence, annoying shouting and he can be insensitive. Sure makes you wonder why they don't go looking for him in Planet Sheen.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: He has enough smarts to write a website, at least. Granted, said website is filled with inaccuracies about Ultra-Lord(like stating he was the father of our country and the creator of the whole planet), but writing and launching a website is still no mean feat in and of itself.
- Goofy Print Underwear: Limited Edition Ultra Lord Underwear! Only available in Japan!
- 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.
- Keet: He's very energetic.
- Loony Fan: He's obsessed with cartoon superhero Ultra Lord.
- Loose Lips: See above.
- Meta Guy: A lot of his Non Sequiturs are lampshades, especially as the show went on. 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..."
- Missing Mom: According to the creators, she died when Sheen was little.
- Plucky Comic Relief: He serves as the funny sidekick on the show.
- Puppy Love: With Libby.
- The Slacker: Watches Ultra-Lord while trying to do his homework
- The Watson: Has his moments.
- Took a Level in Dumbass: He goes through some serious Flanderization in his spin-off show.
- Took a Level in Jerkass: In "Sheen's Brain", he becomes arrogant and rude towards everyone after becoming a genius and that's before he gains telekinetic powers and plots to plunge all of Retroville into darkness and sadisticslly tortures Jimmy and Carl. Finally, he brutally strikes Jimmy and Carl with a lightning bolt and actually kills them. When he sees their dead bodies, he realizes his new powers have turned him into a monster.
- Wide-Eyed Idealist: He believed that there was goodness in Tee and was proven right.
Cynthia "Cindy" Aurora Vortex
Voiced by: Carolyn LawrenceJimmy's rival and female counterpart, who has a crush on him. Not that she'll admit it.
- Abusive Parents:
- Hinted at throughout the show, although the full picture is mostly ambiguous. While it's certain that Mrs. Vortex is a rather strict parent (not much is known about her husband, him being The Voiceless and all) who probably played the key role in developing Cindy's vast ambitions as well as had her enroll in an overwhelming number of extracurricular activities, she genuinely cares for her daughter and supports her at every turn, most notably shown in "Win, Loose, Kaboom" where 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 second 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.
- Badass Bookworm: Other than being smart, Cindy is more athletic than Jimmy and practices a lot of martial arts sports.
- Bare Your Midriff: As Special Girl.
- Belligerent Sexual Tension: With Jimmy.
- Cannot Spit It Out: Cindy's extremely cautious when it comes to saying things she might regret afterwards 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.
- Clingy Jealous Girl: She doesn't like seeing Jimmy showing interest in other girls.
- The Corruptible: Has some experience with that.
- In "The Egg-Pire 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. While she is dumb to trust the Yolkians, so is everybody else in town except Jimmy, and when she realizes that her actions put the whole Retroville in danger she is first to call on others to believe Jimmy and help him bring down Poultra.
- "King of Mars" has her defecting from the gang to join Eustace Strych. 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. That is also why she is Easily Forgiven later on.
- Deadpan Snarker: Often prone to snide remarks.
- Defrosting Ice Queen: Towards Jimmy over the course of the show, as her affection towards him becomes more evident.
- Depending on the Writer: Somewhat averted since there doesn't seem to be any direct link between a particular writer and the way Cindy is portrayed. Then again, you can't help but wonder how she is able to be a mean-spirited bitch in one episode, a genuine if respectable rival to Jimmy in the next and a totally likeable character in the third, only for the cycle to start all over again. Her bad side shines through much more often early in the series but it's still there come the very end. In fact, the inconsistency gets so striking that it appears like some episodes were aired out of chronological order.
- Distaff Counterpart: To Jimmy.
- Expy: Of Helga Pataki. Both of these tomboyish blonde lasses each harbor crushes on the main protagonist but act villainous and bully them whenever they're present, to hide it.
- Flanderization: She was a lot kinder and she and Jimmy got along better in the movie, but now she's become more arrogant, stubborn, snarky and spoiled.
- The Friend Nobody Likes: Cindy is so bossy, loud, stubborn, spoiled and arrogant that hardly anyone can stand her and people even openly call her annoying and pretend to forget her name.
- Girlish Pigtails: In the movie.
- Goofy Print Underwear: Polka dot panties.
- Green-Eyed Monster: At least part of her problem with Jimmy stems from this. In the Movie, she says that she was the smartest kid in her old school until she moved into town and met Jimmy. It's a given that she didn't appreciate being knocked down to second best. It is also shown that she feels inferior to Betty Quinlan and not just because Jimmy likes her.
- Hint Dropping: Unfortunately, Jimmy seems to permanently be holding the Idiot Ball when it comes to interpersonal relations.
- Hypnotize the Princess: Gets hit with this in the Halloween special, courtesy of Vampire!Carl.
- I Know Karate: She actually says this in "King of Mars."
- Jerkass Façade: She's mostly a real jerk to Jimmy because she has a huge crush on him. There's also the hint that she may have a bad home life.
- Jerk with a Heart of Gold: Underneath her harsh, cynical surface she is a genuinely good person, if not at all fond of other people knowing about it:
- She is deeply infatuated with Jimmy and 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.
- 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.
- 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.
- The Lancer: Whenever she accompanies Jimmy on an adventure, much to his annoyance.
- 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's 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), so it sometimes comes as a shock to other kids when she actually uses his first name as well 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. To be honest, Jimmy himself does call Cindy "Vortex" every once in a while but not even nearly as often as she calls him Neutron (and when he does, it usually means he's extremely pissed off with her).
- Little Miss Snarker:
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 toilet in a briefcase!
- In "Trading Faces":
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"!
- "Beach Party Mummy" has this gem of an exchange:
- Loving Bully: She picks on Jimmy but she only does this to mask her love for him.
- Not So Different: In regard to Jimmy. At least early in the series, she constantly makes fun of his alleged nerdiness whereas in fact she loves science just as much as he does, she just can't compare to him in terms of IQ. Also, while her Alpha Bitchy demeanor would suggest otherwise, she isn't really even that much more popular with other kids than Jimmy and aside from Libby and Brittany, she literally has no friends.
- Only Sane Woman: Every once in a while, especially seeing as Jimmy tends to lose the 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 taing the helm doesn't always prove to be the best idea either.
- 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.
- In "The Incredible Shrinking Town", she acts uncharacteristically bitchy and mean spirited to Jimmy, even after he saves their lives from the Space Bandits. To make matters worse, Jimmy was being mercilessly tortured in that episode and at the end, she smashed his well-deserved trophy.
- Pink Means Feminine: Wears pink sneakers and, as seen in the first episode, light-pink panties. Also wore a pink shirt in The Movie. She also decorates her room pink.
- Pride: Like Jimmy, this is one of her trademark flaws. She pretends to dislike Jimmy so people won't laugh at her and doesn't even admit why she resents Betty.
- Puppy Love: With Jimmy.
- Never My Fault: She gives this treatment to her friends when she causes the problem. Particularly in "Vanishing Act".
- Rich Bitch: Played with. Her family does have a big mansion with a swimming pool (and even a butler) but Cindy herself is hardly a typical example of this trope: while it is shown in a couple episodes that she's rather greedy (to the point that she actually takes time to consider whether staying alive is worth of sacrificing her star rubys), she isn't really seen wearing fancy clothes and never once boasts about her family's alleged wealth. In "Granny Baby" she even holds a yard sale. So, we may assume that while her parents are definitely above the national average in terms of income, she doesn't benefit from it too much.
- The Rival: To Jimmy.
- Slap-Slap-Kiss: With Jimmy. Are you starting to get an idea of their relationship yet?
- Spoiled Brat
- Tomboyish Ponytail: In the TV series.
- Took a Level in Kindness: While by no means a bad person, Cindy tends to exhibit somewhat questionable morality, especially in the first two seasons of the show, when she was more often depicted as a semi-villain to Jimmy rather than just his likeable rival/love interest. She can still be a major pain in the butt in season 3 but not as much as before.
- Tsundere: Type A, obviously. In the original 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.
Liberty "Libby" Danielle Folfax
Voiced by: Crystal ScalesCindy's best friend and Sheen's girlfriend and female counterpart. The love of Libby's life? Music, the funkier the better. And she doesn't just listen, she also plays, DJ's, and has pipes that would make most opera singers sick.
- Beta Bitch: She plays this role to her best friend Cindy.
- Beta Couple: With Sheen.
- Big Sister Instinct: Libby serves as a big sister to Jimmy and is always trying to get him to come out of his shell.
- Black Best Friend: To Cindy.
- Deadpan Snarker: Usually when speaking about things she dislikes.
- Fartillery: Gets this when she ate the Belch Boy packet in "The League of Villains" and proves to be better at it than Carl, given that she doesn't need seltzer or to be shaken to burp, and she can eventually control her burping to do it at will.
- 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.
- 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 ability to generate force fields in "The N-Men" episode.
- Not So Above It All: Just like Cindy does with her feelings for Jimmy, Libby sometimes denies her feelings for Sheen.
- Only Sane Woman: Grows into this more and more as the series went on. By the end she's the most levelheaded character in the gang, much to her occasional frustration.
- Pink Means Feminine: Her new design includes a pink long-sleeved shirt.
- Promoted To Opening Credits: Libby is eventually in the title lineup at the end of the opening credits.
- Puppy Love: With Sheen.
- Sassy Black Woman: She's Cindy's sassy Black Best Friend.
- Satellite Character: Was originally one for Cindy, and several of her earliest appearances had her personality as more or less an echo of Cindy's, but as the characters got more development, she became more distinct, particularly regarding her love for music and fashion. Not to mention her new look.
- Shipper on Deck: She's FOREVER pleading with Cindy to just tell Jimmy how she feels and get it over with!
- Token Minority: The only black girl in her group of friends.
- Tomboy: 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".
- Took a Level in Jerkass: In the final episode, she betrays her friends and 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.
- Women Are Wiser: Compared to her boyfriend, Sheen.
- Youthful Freckles: Libby gained some in season 2 after her redesign.
Voiced by: Frank WelkerJimmy's robotic dog.
- A Boy and His X: A Boy And His Robot Dog. Goddard is without a doubt, Jimmy's best friend and favorite invention.
- A Day in the Limelight: Goddard is by all means a main character: he appears at least just as often as Jimmy's parents, Cindy and Libby and is featured prominently in the opening credits, but the first and only episode that gives him the focus is "Best in Show", one of the last ever aired. Other than that, his main occupation is to provide Jimmy with whatever piece of technology or information he is in need of at the moment.
- Do-Anything Robot: He does eleven billion and four things! Except clean up after himself.
- Eating Machine: There's several occasion where it lso eats human foods like ice cream.
- Eye Beams: Among other things it can do.
- Jaw Drop: It has its moment after seeing Jimmy dressed up for his date with Cindy. Being a mechanical robot, its jaw literally dropped.
- Non-Human Sidekick: To Jimmy.
- Robot Buddy: Jimmy's mechanical canine.
- Robot Dog: A robotic dog invented by Jimmy himself.
- Self-Destruct Mechanism: Its "plays dead" command is this. Goddard can reassemble itself despite its 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: For Jimmy and the rest of his gang.
Hubert "Hugh" Beaumont Neutron
Voiced by: Mark DeCarloJimmy's father. Averts Father Knows Best. 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. Has an obsession with ducks.
- Adults Are Useless: Played straight with Jimmy's dad in the TV series, who is probably one of the biggest idiots in the city.
- Bumbling Dad: Many times, Hugh would screw up one of Jimmy's inventions.
- Cloudcuckoolander: Quite possibly the largest one in the series.
- The Ditz: The typical dim-witted bumbling father.
- Gasshole: Even without drinking the Burping Soda, Hugh has burped more than anyone else in the series, including Carl.
- Happily Married: To Judy.
- Idiot Ball: Holds it consistently, like it's his firstborn child.
- 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 then non-popular restaraunt McSpankies, to make his parents rich and allowing him to get an expensive set of encylopedias 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 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 embarassing 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 popstar. He even initially refuses to save his son's life before his parental instincts finally kick in and revert him back to normal.
- Trademark Favorite Food: Pie.
- "Jump Off a Bridge" Rebuttal: Twisted.Jimmy: "Aw, but Dad! All my friends are going!"Hugh: "Now, Son, if all your friends were named Cliff, would you jump off them?"
- Obliquely Obfuscated Occupation: Eventually averted when we learn he's a car salesman.
- Ugly Guy, Hot Wife: With Judy.
Judith "Judy" Neutron
Voiced by: Megan CavanaghJimmy'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.
- Action Mom: She's incredibly athletic, coordinated, intelligent, and she keeps a plasma rifle in her utility closet (for those tough ground-in stains!)
- Beauty Mark: Has one near her mouth.
- Deadpan SnarkerJudy: 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.
- Full Name Ultimatum: "James Issac Neutron!"
- Gasshole: Becomes this after chugging some of Jimmy's Burping Soda.
- Happily Married: To Hugh.
- Hypnotize the Princess: Ever noticed she gets hypnotized quite a bit on this show?
- Mama Bear: "Get away from my family, you ugly bucket of bolts!"
- Mundane Utility: Use a demolecular cannon beam to clean difficult stains.
- Only Sane Woman: Along with Libby.
- Stacy's Mom: Carl has a crush on her.
- Ugly Guy, Hot Wife: With Hugh.
- Women Are Wiser: Compared to her bumbling husband.
Voiced by: Candi MiloAnother one of Jimmy's best friends, who is the cool guy that everybody loves at school, especially the girls.
- All Girls Want Bad Boys: Which is why all the girls at his school dig him.
- 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
- Butt Monkey: All of his later appearances 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
- Demoted to Extra: Earlier episodes were building him up to be an important character. Then he vanished. Now he barely shows up at all except to break his leg skateboarding. He even got his own toy in the Wendy's Kid's Meals when the original film came out. 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: He is a bit of a mama's boy.
- Flanderization: In the movie, Jimmy takes 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.
- 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.
- Jerk with a Heart of Gold: Nick may be cynical and snarky, but he's also one of Jimmy's best friends.
- Lovable Jock: One of Jimmy's best friends and the most athletic one (next to Cindy).
- Meaningful Name: His last name is a reference to James Dean who is best known for playing similar "bad boy" roles.
- 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. And it only goes downhill from there…
- Pretty Boy
- Screams Like a Little Girl: Whenever something frightens him.
- The Sixth Ranger
- Troubled, but Cute: A supposed tough kid who is considered cool and is popular with girls.
Voiced by: Phil LaMarr
- 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 or Rolf. The difference is that Bolbi's country is actually named (Backhairistan).
- Hidden Depths: He's a very good actor and has monologues committed to memory.
- Ruritania: His homeland of Backhairistan.
- Strong Family Resemblance: His sister is just a slightly shorter version of him in blonde braids.
- The Sixth Ranger: Starts taking a role similar to this in later episodes.
- Trademark Favorite Food: Kebabs. They appear to be standard cuisine in his country.
- Vocal Evolution: Had a slightly deeper voice and heavier accent in his first appearance.
Voiced by: Kath SoucieThe girl of Jimmy's dreams, and sometimes the motivation for hi jinks in his effort to impress. Cindy doesn't care for her... for some reason.
- A Day in the Limelight: She's the main protagonist of "Out Darn Spotlight".
- Bare Your Midriff: When she played Lady Macbeth.
- Betty and Veronica: Quite literally the sweet natured Betty to Cindy's Veronica. Ironically, Betty looks like Veronica and Cindy looks like Betty.
- Beauty Mark
- 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 doesn't get any true focus outside of Jimmy's love glazed POV. Finally subverted a bit when we see, that despite her pleasant demeanor, she does have her limits. And no, she's not oblivious to Jimmy's crush on her (she'd have to be deaf, dumb, and blind, actually), 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.
Voiced by: Frank Welker
- Berserk Button: MUSIC. 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 as well as the Crites from Critters.
- Fish Eyes: They have them.
- Killer Rabbit
- 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.
Voiced by: Andrea MartinThe cast's homeroom teacher.
- Animal Motifs: Birds. Not just her name, but her appearance (long pointy nose, motioning her arms like wings, squawking, etc.).
- 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 a fourth grade education ("And that's why cowboys are bow-legged" anyone?).
- 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.
- Gag Nose: Resembling a beak, taking her whole bird motif much further.
- Kavorka Man: A rare female example. She attracted Thomas Edison, went dancing with President Hoover, flirts with Sam and was once married to a werewolf.
- Noodle Incident: She was once married to a werewolf. She refers to it as "a story for another day".
- Stern Teacher: She has her moments.
- Vague Age: Okay, she's old. But how old is she?
Sheen: She is getting on in years, but I'm sure she's not a thousand.
- 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.
- Verbal Tic: Tends to end sentences with a squawk-like noise.
Voiced by: Billy WestOwner of the local hangout joint, The Candy Bar.
- 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. Granted something should have been done to try to help the kids control their new found powers. However, calling the military up to imprison them and then telling the kid's parents they were just freaks?
- Ship Tease: Sometimes has these with Ms. Fowl.
- Verbal Tic: Has a habit of ending his sentences with, "Yeah!".
Voiced by: Patrick Stewart (movie), S. Scott Bullock (TV series)King of the Yolkians, and Jimmy Neutron's archenemy.
- Arch-Enemy: To Jimmy.
- Big Bad: He is the main villain in the movie.
- Legion of Doom: He created "League of Villains" consisting of several villains from numerous episodes including some of the Rogue Galleries.
- Taught by Experience: Goobot learned from past experiences that Goddard, Jimmy's inventions and friends were things that foiled his plans so he cut down Jimmy's access to them before catching him in "League of Villains".
- Trapped in the Past: What presumably becomes his ultimate fate at the end of League of Villains episode. Considering that we see Eustace Strych in third crossover with The Fairly OddParents, he's presumably able to go out.
Professor Finbarr Calamitous
Voiced by: Tim CurryJimmy's arch-nemesis and the show's main antagonist.
- 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 "League of Villains".
- 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. Jimmy himself lampshades this:Jimmy: "For a bumbling genius, he's pretty dangerous."
- Big Bad: Expect him to fall into this role a lot, especially during crossovers.
- Dope Slap: Often gets these from his daughter.
- Evil Counterpart: To Jimmy, although he's much older.
- In Their Own Image: After being fused with 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. The only thing he hadn't finished was putting in a bathroom.
- 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.
- Would Hurt a Child: Considering the showdown he usually has with Jimmy, this trope suits him. In crossover with The Fairly OddParents, he ouright tried to kill him using Jorgen's magic. Thankfully, fairy magic is not made to harm.
Voiced by: Wendie MalickProfessor Calamitous's daughter. Her real name's Georgia Calamitous. Jimmy, Carl, and Sheen are easily seduced by her looks.
- Annoying Laugh: Snorting variation in every full, uninterrupted Evil Laugh. Sheen even lampshades it.
- Beauty Mark: On her right cheek near the upper lip.
- Beleaguered Assistant: In Operation: Jet Fusion. She often bemoans having to do Calamitous's 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 majority of Bond villain. Considering her debut is in an episode parodying spies film, it's to be expected.
- 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
- Interspecies Romance: With 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: Her dad wasn't exactly very creative with the name. Or subtle.
- Mind-Control Device: She made one to hypnotize Jet Fusion in the form of a box candy. Also did this Jimmy with his Hypno Ray.
- Ms. Fanservice: The name should be a tip off, but the way Jimmy, Sheen and Carl react to her in her debut pretty much cements it.
- 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.
- 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"...
- Ugly Guy, Hot Wife: With Junkman.
Voiced by: Tim AllenThe host of the hit game show "Intergalactic Showdown" and the main villain of the TV movie "Win Lose and Kaboom".
- Big Bad: Of "Win Lose And Kaboom".
- Doing In the Wizard: His seemingly supernatural hold over reality, time and space is actually caused by a pair of matrix generators hidden in his cuff links.
- 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.
- 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.
- Karma Houdini: The worst he gets is being forced to hand over his show to the Brain aliens and advertise an exercise machine that implements Electric Torture. Probably justified as he's implied to be indestructible.
- Large Ham: He's a Game Show host. It comes with the territory.
- Omnicidal Maniac: "Winner gets a brand new car! Loser gets their home planet destroyed!"
- The Omnipotent/Reality Warper: Thanks to the matrix generators in his cuff links.
- Smug Snake: He's definitely dangerous, but his pride makes him rather short-sighted.
- Time Abyss: Implied, as April states that his show has existed for eons.
- Villainous Breakdown: Loses it when he discovers that his show is about to be destroyed.
Zix, Travoltron, and Tee
- 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 League of Villains. This and Sheen's willing to hear his story were what triggered his Heel–Face Turn.
- Good Feels Good: What Zix and Travoltron thought after helping Jimmy and friends, indicating that their Heel–Face Turn would be permanent.
- Finger Gun: All three of them use this motion when shooting some kind of gooey substance used in sealing Jimmy's lab.
- Heel–Face Turn: Tee during Jimmy and Sheen's imprisonment. Zix and Travoltron followed during the casts' time in Cretaceous Era.
- Man Hug: Tee really likes to give this. Well, a bit too much. Travoltron too, to a lesser extent.
- Real Men Hate Affection: In contrary to Tee and Travoltron, Zix hates Man Hug but he will accept a handshake with his teammates.
- Speaks Fluent Animal: They can only understand and speaks lizards language though since they said they were in the same family as them. They used this ability to distract and send a T-rex away from eating Jimmy and his friends.
- Verbal Tic: Tee tends to have "Fool!" in most of his sentence.
Edward "Eddie" Neutron
Voiced by: Mark DeCarloJimmy's 17,5-month-old cousin commonly called by people as "baby Eddie". Despite his baby-looking appearance, he's actually very genius; capable of walking, speaking fluently, and devising plan to kill all of Neutron family member. He's one of members of "League of Villains" created by Goobot.
- 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.
- Bitch in Sheep's Clothing: His first appearance. Since his identity had been covered, he dropped the nice appearance in subsequent appearances.
- Casanova Wannabe: Tried flirting with Beautiful Gorgeus with negative results.
- Charlie Brown Baldness: Has one visible gravity-defying strand of hair only. Justified somehow that he's still a baby.
- Cool Bike: His motorcycle can frickin' bring him to space. Too bad it only appeared in "Bad guys assemble montage" at the beginning of "League of Villains" episode.
- Enfant Terrible: Duh.
- Evil Genius: Who knows a 17,5-month-old baby can outsmart Jimmy ar 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 petite appearance.
- Expy: He has several similarities with Stewie Griffin, both are baby geniuses with a rather unbabylike attitude.
- Only Sane Man: Putting aside his need to change diapers, he's mostly this with King Goobot.
- 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 League of Villain debated on how to kill Jimmy Neutron using convoluted (or even silly) ways, he stepped up and said "Just blow him into deep space!" to which everyone agreed.
Voiced by: Rob PaulsenA snobby rich kid who buys all of his gadgets from his dad. He's one of members of "League of Villains" created by Goobot.
- Bad Boss: He uses his personal butler, Blix as an abuse dummy.
- 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 while he's a spoiled brat.
- Jerkass: He's very rude to everyone, especially Jimmy. And he was using Cindy's love to emotionally crush Jimmy and then, he forced Jimmy to watch Goddard die.
- 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 jerk.
- Sanity Slippage: Later episodes imply that his vendetta against Jimmy has left him with a few screws loose. He even lampshades this trope while laughing insanely!
- Smug Snake: Probably one of the less threatening antagonists Jimmy has faced.
- 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.