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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?
Full Name: James Isaac Neutron
- Adaptation Personality Change: In the movie, he was 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 if he was a boy genius.
- Adorkable: An adorable and dorky boy genius, who happens to be the main character. This was more evident in the movie and shorts.
- Adorably Precocious Child: During the movie (and to a degree, season one).
- 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?
- 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.
- 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.
- Belligerent Sexual Tension: With Cindy.
- 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 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 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*
- It even happens with a similar situation where in Jimmy Neutron vs. Jimmy Negatron, where Cindy falls in love with Negatron.Jimmy: Not that! Anything but that! "NOOOOOOOOOOOOOOOOOO!"
- 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.
- 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.
- 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 the Yolkians trap them in the park and sic Poultra on them.
- 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.)
- Chick Magnet: He gets a lot of attention from girls both in-universe and in fandom.
- Child Prodigy: A teenage boy genius who has an impossible IQ of 210.
- Cheaters Never Prosper:
Tremendous Jackson: Somewhere in the Rytridian Galaxy, Ultra Lord weeps.
- In "Maximum Hugh", he and Hugh are disqualified from the picnic games along with the other families for cheating.
- 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:
- In "Jimmy for President", he gets caught cheating to win the election and is disqualified.
- 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: In season three'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.
- Department of Redundancy Department: Has a tendency to do this a lot.
- Ditzy Genius: He's undeniably smart, but has a lack of common sense and can be arrogant.
- Drunk with Power: In "Hall Monster".
- Expy: He's very similar to Dexter, being a diminutive and easily frustrated boy genius who has his own laboratory which leads to hilarious mishaps. One 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.
- The Friend Nobody Likes: However, even though it is shown that while his friends don't like him, it doesn't mean they don't care about him especially in Lights Camera Danger.
- 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 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.
- Hulk Out: His actual superpower in "The N-Men". He becomes The Incredible Hulk with elements of The Thing of the Fantastic Four, granting him inhuman strength, agility, and a Healing Factor.
- Give Geeks a Chance: He gets a lot of attention from girls both in and out of universe.
- 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 doesn't mean 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.
- Jerk with a Heart of Gold: Jimmy tends to be arrogant and snarky, creating various inventions for his own selfish intentions. However, in the end, he will do the right thing.
- Kid Hero: Jimmy is only an elementary school student but always saves the day from trouble, albeit caused by his own mistakes.
- Little Professor Dialogue: Well he does actually have an IQ of 210.
- Lovable Nerd: Which is why girls in and out-of universe love him.
- Nerds Are Innocent: He's an adorable and dorky child prodigy who loves and excels at science...and still believes in cooties.
- Nerds Love Tough Schoolwork: Completely averted - in fact, Jimmy hates school, just like any normal kid.
- Never My Fault: He gives this treatment to Cindy towards the end of the series. A good example would be in "King of Mars".
- 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. In "The Incredible Shrinking Town", Libby remarks that Jimmy's endangered the town so often that she's just Stopped Caring.
- No Social Skills: He's not very social. He keeps telling himself to work on them.
- Odd Friendship: An adorable boy genius who is best friends with an asthmatic hefty boy who's obsessed with llamas, a hyperactive Aztecan kid who's obsessed with a superhero, a skateboarding bad boy, his academic rival, a sassy girl who loves music and a ditzy dumb blonde.
- 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.
- Sensitive Guy and Manly Man: The sensitive guy to Nick's manly man in the film.
- Sesquipedalian Loquaciousness: A frequent user and abuser.
- Slap-Slap-Kiss: With Cindy.
- 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.
- Took a Level in Dumbass: He tends to let his overconfidence and arrogance get the best of him quite a few times.
- Took a Level in Jerkass: Towards season three, he becomes more irritable and hostile towards his friends, probably due to all those years of insults and them being uncooperative particularly in Carl Wheezer Boy Genius and The N Men.
- TV Genius: He is a teenage 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.
- 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 and sounded a lot more like Nergal Junior. Now his voice is 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.
Voiced by: Rob Paulsen, Wally Wingert (Jimmy Neutron Boy Genius console game)Jimmy's shy, asthmatic best friend who has an unhealthy obsession with llamas and Jimmy's mom.
Full Name: Carlton Ulysses Wheezer
- 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 your toys, not eat them.Carl: I know. But they always look so chewy and colorful.
- 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.
- 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: To Jimmy.
- Catch-Phrase: "My scapula..."
- 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.
- 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. 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'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.
- Never My Fault: He gives this treatment to Jimmy in "Attack of the Twonkies" and "Carl Wheezer: Boy Genius".
- Ow, My Body Part!: He seems to have a really tender scapula.
- Precocious Crush: On Jimmy's mom.
- 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: To Jimmy's mom.
- 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 Friends Like These...: He and Sheen can act like this way towards Jimmy by laughing with Cindy & Libby when they bully Jimmy and the one time when Jimmy told him and Sheen not to tell the other kids about his weather invention going haywire, but they told the kids anyway, causing the kids to be (albeit understandably) angry with Jimmy. 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.
Voiced by: Jeff GarciaOne of Jimmy's best friends 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". 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.
- 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 fourth 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: [to Jimmy, Cindy and Libby] Guys, what're you so worried about? Ultra Lord's going to be here any minute.Cindy: Ultra Lord's not coming you ding-dong! The Yolkians lied to you!Sheen: [gasps] WHAT?! Then they have awakened the wrath of Sheen! What're your orders Jimmy?!
- 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.
- 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 three, 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.
- 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.
- 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.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 wrote the entire Ultra Lord website, which claims that he's the father of our country.
- 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.
- 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 his normal self.
- In "Jimmy for President", he 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.
- 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.
- Keet: He's very energetic.
- 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..."
- Missing Mom: According to the creators, she died when Sheen was too young to remember her.
- No Indoor Voice: Especially in season three.
- Plucky Comic Relief: He serves as the funny sidekick on the show.
- Puppy Love: With Libby.
- Red Oni, Blue Oni: The red to Nick's 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.
- 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 & Libby when they bully Jimmy and the one time when Jimmy told him and Carl not to tell the other kids about his weather invention going haywire, but they told the kids anyway, causing the 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.
Voiced by: Carolyn LawrenceJimmy's rival and female counterpart, who has a crush on him. Not that she'll admit it.
Real name: Cynthia Aurora Vortex
- 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.
- Adorkable: Particularly in the movie when she's explaining to Libby how she is mixing ta chi with purple flurp.
- Badass Bookworm: Other than being a genius, Cindy is more athletic than Jimmy and practices a lot of martial arts sports.
- Bad Liar: Cindy is the worst liar in the world.
- 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 any interest in other girls, most notably Betty.
- The Corruptible: She tends to get easily flattered by the villains into helping them.
- Deadpan Snarker: She's often prone to sassy remarks.
Jimmy: I don't understand it. I can't seem to find the lost tomb!
- For example "Beach Party Mummy" has this exchange:
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.
- 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: In the movie, she was revealed to be a lot kinder than she seemed and she and Jimmy got along better as result by films end. In the series, she's become more stubborn and she and Jimmy fight more. In the cancelled season four, Cindy would've been de-Flanderized, since she and Jimmy would become official.
- Girlish Pigtails: In the movie and shorts before trading it to a ponytail.
- Goofy Print Underwear: Polka dot panties.
- Green-Eyed Monster:
- She was the smartest kid in her old school until she moved into town and met Jimmy.
- It is also shown that she feels inferior to Betty Quinlan, and not just because Jimmy likes her. This would've been further explored in Season 4.
- 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.
- Hypnotize the Princess: Gets hit with this in the Halloween special, courtesy of Vampire!Carl.
- 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 Façade: She's spoiled, stubborn, arrogant and bossy, but uses them to cover up her insecurities.
- Jerk with a Heart of Gold:
- She's bossy, spoiled, stubborn and arrogant, 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.
- 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'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) 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 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".
- Nice Job Breaking It, Hero!:
- 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, though she is 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 unconcious, 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.
- "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 is also why she is Easily Forgiven later on.
- Not So Different:
- She constantly makes fun of Jimmy being super smart, when in fact, she is a genius just like him, but not as big a genius as him.
- Also, while her Alpha Bitchy demeanor would suggest otherwise, she and Jimmy are both The Friend Nobody Likes and the townsfolk even consider her just as much a nuisance as Jimmy.
- Nice Mean And In Between: The mean one with Libby and Brittany.
- 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. 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.
- Rich Bitch: She's rich and is rather greedy when it comes to diamonds and jewels.
- The Rival: To Jimmy.
- 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.
- Slap-Slap-Kiss: With Jimmy.
- Spoiled Brat: Kind of like Cera as a human.
- Tomboy and Girly Girl: The Tomboy to Libby's Girly Girl.
- Tomboyish Ponytail: In the TV series.
- 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.
- Women Are Wiser: 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 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.
Voiced by: Crystal Scales, Carolyn Lawrence (Jimmy Neutron Vs. Jimmy Negatron)Cindy's best friend and Sheen's girlfriend. The love of Libby's life? Music, the funkier the better. And she doesn't just listen, she also plays the keyboard, DJ's, and can throw a high note that would give most opera singers a run for their money.
Real name: Liberty Danielle Folfax
- 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.
- Black Best Friend: To Cindy.
- 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.
- Deadpan Snarker:Sheen: Don't worry, Libby. When I'm elected, you can still be my First Lady.Libby: Get a life, Sheen.
- 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.
- Nice Mean And In Between: The in-between one with Cindy and Brittany.
- 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.
- O.O.C. Is Serious Business: Whenever she lies.
- 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.
- Promoted to Opening Credits: Libby is in the title lineup at the end of the opening credits of season three.
- Puppy Love: With Sheen.
- 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 Minority: The only black girl in her group of friends.
- 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.
- Took a Level in Jerkass: In "Lady Sings the News", she 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.
- True Companions: With Cindy and Brittany.
- Women Are Wiser: Compared to her boyfriend, Sheen.
Voiced by: Frank WelkerJimmy's robot dog and lab assistant.
- 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, 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 billion and four things! Except clean up after himself.
- Eating Machine: There's several occasion where he also eats human foods like ice cream.
- Jaw Drop: He has this moment after seeing Jimmy dressed up for his date with Cindy. Being a robot, his jaw literally dropped.
- Non-Human Sidekick: To Jimmy.
- 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 gangs mascot.
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.
Real names: Hubert Beaumont Neutron
- Adaptational Personality Change: Hugh is very much like a normal, well-meaning, loving father in the movie. To give him more of a distinct personality, the series made him more bumbling and naive.
- Adults Are Useless: Hugh is probably one of the biggest idiots in the city. In fact, he messes with Jimmy's inventions all the time.
- 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 restaurant McSpankies, to make his parents rich and allowing 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 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 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?"
- Manchild: Probably the least intelligent person in Retroville, rivaling even Carl and Sheen. The guy's obsessed with ducks and pies, come up with childish theories and acts as if he is a ten year old. The only person who could rival his childishness is probably Timmy Turner's dad.
- 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 Job Breaking It, Hero!: Sometimes he causes the episodes problem.
- Obliquely Obfuscated Occupation: Eventually averted when we learn he's a car salesman.
- Ugly Guy, Hot Wife: With Judy.
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.
- '50s Hair: Lampshaded in "Maternatron Knows Best".
- A Day in the Limelight: 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!)
- 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?
- Hypocritical Humor: She says the identical-looking robot mom has a "hideous 1950's hairdo".
- Mama Bear: "Get away from my family, you ugly bucket of bolts!"
- Mundane Utility: Use a de-molecular cannon beam to clean difficult stains.
- Only Sane Woman: Along with Libby.
- Stacy's Mom: Carl has a crush on her.
- Took a Level in Jerkass: In season three, she's more hostile towards Jimmy.
- Ugly Guy, Hot Wife: With Hugh.
- Women Are Wiser: Compared to her bumbling husband.
Voiced by: Phil LaMarrA 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.
- 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 has monologues committed to memory.
- Killed Offscreen: Implied. His last on-screen appearance in the series was being chased by a rampaging monster unleashed by Professor Calamitus.
- 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" and "Out Darn Spotlight".
- 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.
Voiced by: Kath SoucieThe 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.
- A Day in the Limelight: She's the main protagonist and focus of "Out Darn Spotlight" and "Vanishing Act".
- 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.
- Beware the Nice Ones: In her later appearances, when we see that she has her limits.
- Beauty Mark: Located under her right eye.
- Distaff Counterpart: To Nick.
- 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.
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.).
- Up to Eleven in "I Dream of Jimmy" where 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 a fourth grade 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.
- 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.
- 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".
- 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.
- Lampshaded in "Attack of the Twonkies".
- Verbal Tic: Tends to end sentences with a squawk-like noise.
Voiced by: Candi MiloAnother one of Jimmy's friends, who is the cool guy that everybody loves at school, especially the girls.
- Adaptational Nice Guy: He's much nicer and fleshed out than he was in the movie.
- Adaptational Wimp: 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.
- All Girls Want Bad Boys: Which is why all the girls at his school dig him.
- 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 Haughty: In "The League of Villains", it is implied he now hates himself.
- The Chew Toy: All of his appearances in season three 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 SnarkerSheen: 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: He 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: He is a bit of a mama's boy.
- 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.
- 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.
- 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.
- Odd Friendship: He and Jimmy have a strong bond and get along well.
- 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.
Voiced by Candi MiloCindy's other best friend, who is often seen hanging out with her and Libby as a third member of Cindy's friend circle.
- Adorkable: She's clumsy, naive, innocent, downright adorable and as sweet as a jellybean. Especially when Nick's around.
- 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 four.
- Bare Your Midriff: She wears a pink and white midriff shirt.
- Book Dumb: In "Raise of the Oozy Scab", Brittany is revealed to be illiterate.
- 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.
- Morality Pet: To Nick.
- Never Learned to Read: Which she sometimes denies.
- 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: The nice one with Cindy and Libby.
- No Celebrities Were Harmed: "Um, I didn't do it!"
- Savvy Guy, Energetic Girl: The energetic girl to Nick's savvy guy.
- Simpleton Voice: Candi Milo at her best.
- True Companions: With Cindy and Libby.
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. He was right that 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 was beyond the pale.
- 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!".
King Goobot the Fifth
Voiced by: Patrick Stewart (movie), S. Scott Bullock (TV series), Joe Whyte (video game)King of the Yokians, and Jimmy's first archenemy.
- Arch-Enemy: To Jimmy.
- Big Bad: He is the main villain in the movie.
- Greater-Scope Villain: Of the PC Jimmy Neutron game.
- Legion of Doom: He created "The 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 the series finale.
- Trapped in the Past: What becomes his ultimate fate in the series finale.
Voiced by: Martin Short (movie), Paul Greenberg (TV series), Mark DeCarlo (video game)King Goobot's less than competent assistant.
- Affably Evil: He's unfailingly polite even when he helps Goobot with his wicked whims.
- Cloudcuckoolander: He's not too bright.
- 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.
- Put on a Bus: Goobot apparently traded him for sulfur butter prior to "League of Villains".
Yokian Fleet Commander
- Canon Foreigner: He is made for the PC Jimmy Neutron game.
- Creepy Monotone: His voice is full of this.
- Darth Vader Clone: His shell is mostly black and an important figure for the true main villain. In fact, he even QUOTED Darth Vader.
- 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.
The Yokians' "god(ess)", a gigantic chicken monster.
- Ambiguous Gender: In the film, he's referred to as male and a "god", but in "Return of the Yolkians", she's referred to by female pronouns. This may be justified because the Poultra who appeared in "Return of the Yolkians" 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: Possible subversion—she was killed in the movie, but in the TV special "Return of the Yolkians" she's brought back. The reason it's possibly a subversion is because she's more or less cloned back to life and Jimmy implies that the cloned Poultra isn't the same as the original one.
- Feathered Fiend: A giant killer chicken.
- Shout-Out: Her second death is a shout out to the Wawel Dragon, of all things.
Professor Finbarr Calamitous
Voiced by: Tim CurryJimmy's other 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 "The League of Villains".
- Affably Evil: Sure, he's got evil scheme after evil scheme, but he's still a pretty friendly guy.
- 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: "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 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. 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.
- Affably Evil: Much like her dad.
- 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 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: 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: Understatement of the year.
- 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"...
- 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: Presumably, she got her looks from her mother.
Voiced by: Debi DerryberryAn evil boy genius who lives in the Evil Dimension.
- Beard of Evil: He has a goatee, even for a preteen.
- 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 Twin: Of Jimmy Neutron.
- Faux Affably Evil: He seemed gentle to Neutron at first, but he is evil after all.
- For the Evulz: He is an EVIL Boy Genius.
Voiced by: Rob PaulsenA creation of Jimmy Negatron who can travel through time.
- 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 to imprison Negatron.
- 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.
- Skele Bot 9000: He is a robotic skeleton.
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.
- Beware the Silly Ones: Their personalities and bickering is mostly comical. However, these two are easily among the most dangerous antagonists in the series as their second appearance was literally seconds away from the extinction of the human race.
- Fat and Skinny: 01 is shorter and rounder while 02 is tall and lanky.
- Knights 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 is so bad it 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!
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.
- Knight of Cerebus: He is more than capable of destroying planets and transmitting matter and energy, courtesy of his matrix generators.
- 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.
- 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 the League of Villains. This and Sheen's willingness to hear his story out were what triggered his Heel–Face Turn.
- Good Feels Good: What Zix and Travoltron thought after helping Jimmy and friends, showing 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.
- No Celebrities Were Harmed:
- 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: They can only understand and speaks lizards' language, 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 sentences.
- 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 (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.
Voiced by: Charlie Adler
- 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: Charlie Adler at his best.
- 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.
- Unholy Matrimony: Parodied when Jimmy uses a love potion on him and Beautiful Gorgeous. Their hatred for each other promptly becomes love.
Voiced by: Mark DeCarloJimmy'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.
- 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 uncovered, he dropped the nice facade in subsequent appearances.
- 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.
- Expy: He has several similarities with Stewie Griffin, both are baby geniuses wih 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 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.
- Trapped in the Past: His official defeat.
- 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.
- 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.
- Evil Is Petty: He is a petty, sadistic jerk.
- Hate Sink: Just look at his tropes.
- Jerkass: He's very rude to everyone, especially Jimmy, and he used Cindy's love to emotionally crush Jimmy and then, he forced Jimmy to watch Goddard die.
- 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.
- 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.
- Trapped in the Past: His fate in the series finale.
Voiced by: Edie McClurg
- 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.
- 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.
- 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.