List of Jimmy Neutron characters

This is a list of characters in the American television animated series The Adventures of Jimmy Neutron: Boy Genius.

Main characters

Jimmy Neutron

Jimmy Neutron The main protagonist of the series is a super intelligent boy who uses scientific knowledge and innovations to solve issues he is confronted by (most of which he causes himself). He is the son of Hugh & Judy Neutron. His best friends are Carl Wheezer & Sheen Estevez who often end up as test subjects for his experiments & inventions. At the beginning of the series Cindy Vortex is his most important rival, but he secretly feels attracted to her (and vice versa). The latter only came to true expression in the episode "Love Potion 976/J" in which he is accidentally exposed to the effects of a love potion he created himself. This caused him to fall in love with the first girl he'd see, which in this case was Cindy. Later in the episode he proclaims his love for her at the "Candy Bar".

Carl Wheezer

Jimmy's Best Friend. Carl is allergic to lots of things, including cats, turtles and even lasers. Yet he still helps Jimmy with his experiments. In the movie, Carl wore suspenders but in the TV show he doesn't. In a few episodes it is shown that Carl has a crush on Jimmy's mom. Although Carl didn't make a in-person appearance on Planet Sheen, he appears in one of Sheen's flashbacks. Carl also has a massive obsession over Llamas. While often dismissed by the group of friends, Carl often saves the day and utters occasional pearls of wisdom which belie his station as resident nebish: "The heart wants what the heart wants" "I can not be a genius 24/7!" and "I don't want to be cool." It is also said he has an sensitive scapula. He makes an non-physical cameo in the spin-off show Planet Sheen t.v. show, the appearance happens when Sheen meets Carl's counter-part Doppy, he sees similarities between Doppy and Carl and haves a flashback to him and Carl's times on earth before he went to Zeenu [the planet Sheen flew to].

Cindy Vortex

Jimmy's sassy, 11 year old independent, intellectual rival. She has a dog named "Humphrey" who she says is the best dog in Retroville. Her best friend is Libby Folfax. In the movie Cindy in seen wearing a pink buttoned shirt, black jeans, pink shoes, and her hair styled in pigtails. This design of Cindy was used more often for Jimmy Neutron videogames. Also in the mini clip of Jimmy Neutron entitled 'New Dog; Old Tricks', Cindy wears a pink skirt. But in the TV show her hair is styled into a ponytail with a green halter top, khaki pants, and pink converse shoes. She has a secret crush on Jimmy, the show gives little hints of it throughout the seasons, but doesn't actually show it until Season 3. Although not confirmed, it is possible she might appear in Planet Sheen. She was born June 5, 1991.

Sheen Estevez

Voiced by: Jeffrey Garcia. Sheen Juarerra Estevez is Jimmy's other best friend, a hyperactive 13 year-old boy who is known for his obsession with a fictional superhero called "Ultra Lord" who stars in a television program that Sheen frequently watches (perhaps unsurprisingly, Sheen wrote the entire "Ultra Lord" website on the Internet). Sheen is also a fan of Speed Metal. At times Sheen's hyperactive personality boils over, often causing him to scare Carl. He is also best friends with Carl. In Operation: Rescue Jet Fusion (a spoof of James Bond) Sheen states that he is Mexican. Sheen's name is a parody of the Estevez-Sheen family of actors consisting of many famous actors such as Martin Sheen and his sons Emilio, Ramon, Carlos (a.k.a. Charlie Sheen) and Renee.

Besides having a loud voice, Sheen is older than most of his classmates, but it's not because Sheen was held back a year, but because his father made him start kindergarten a year late because he was shy as a young child. Sheen's mother was mentioned but has never appeared in the series before. Sheen also has an unseen younger sister, but she was only mentioned in "I Dream Of Jimmy" when she argued with Sheen about the possible existence of the "Potty Fairy." Sheen also has an ongoing crush on Libby Folfax, and at the beginning of the series she constantly taunted and rejected Sheen just how Cindy was with Jimmy before their romance blossomed. Towards the end of the series, however, Libby agreed to be Sheen's girlfriend, which gave him the strength to fight an enemy in one episode. Of all the characters on "Jimmy Neutron", Sheen acts the oddest. In one episode he is the only person who continually ate the literally-shocking candy that Jimmy invented and in two others (though throughout the series he has a liking to be shocked by anything electrical), when it seems the Earth will be destroyed, Sheen is only interested in winning a contest and becomes upset when he realizes the monster truck rally will be held the day after doomsday. His head is shaped like a cone. He can also play guitar, seen in the episode "El Magnifico".

He appears as the main protagonist in the spin-off Planet Sheen.[1]

Nick Dean

The "Cool" Kid at School. Often seen on a skateboard, doing dangerous tricks. He doesn't do show and tell, shows up to school five minutes before dismissal sometimes, and is obsessed with styling his hair. He is considered very handsome by all girls in the school. He is also of Brazilian American descent and breaks his leg from time to time on his skateboard, when he does so he usually lets out a high pitched girly scream. Nick also has a mother who can speak Portuguese and English. He was originally going to be part of the regular gang; (In the movie he had that role more than Libby) and Libby would be one of the supporting kids such as Butch or Oleander. He is one of the towns' wealthist children, living in a 92 room mansion, with a bowling alley, maids' quarters, a screening room, and a soda parlor. He can also sing operatic German, and can style his hair without using his hands. Voiced by Candi Milo. In the movie, he was almost always seen with a purple lollipop in his mouth. He is very strong as shown in one episode he was able to beat up Jimmy, Carl, and Sheen and throw all three of them in the dumpster. However, he can be a coward at times and even a wimp as in the movie when he confronted Poultra, he ran away screaming like a girl. He wore a sleeves jacket for the first half of the series then switched to a leather jacket.

Libby Folfax

Cindy's best friend. She loves funk/hip-hop and electronic gadgets. Later on in the show, she received a brand-new hair makeover and a striped-pink shirt. Libby is 11, and in the first season she does not appear on the title logo, however when she becomes more involved in the show in the second season, she is added to the logo. Unlike Jimmy's friends, Libby is shown to do well in school, though isn't at the level of Jimmy or Cindy in terms of intellect. In the movie and Season 1, Libby's hair is up in a bun, with a large bang covering her eye. She wears a green dress, green socks, and black dress shoes. In the episode Beach Party Mummy, she got a makeover with her new cornrow braids, pink shirt, blue jean pants, and brown shoes.

Goddard

Jimmy's trusty robotic dog. He is made of sprockets, circuits and widgets, and makes a great man's best friend. One of the best dogs by Jimmy.

Other characters

Other characters in The Adventures of Jimmy Neutron: Boy Genius are listed below:

A

• Algae Men, the henchmen of Dr. Sydney Moist, a crazed scientist gone bad who lives on the ocean floor. It was later revealed that Dr. Moist was using a mutagen to turn innocent tourists into algae men, which explains the rash of disappearances in the Bahama Quadrangle.

• Aunt Amanda, Jimmy's wealthy aunt, she hates Jimmy Neutron because he brings danger to the town. She reconciled with him after revealing his evil, baby cousin's plan. Appears only in the episode "Clash of the Cousins".

• Aunt Kari, Jimmy's aunt and Baby Eddie's mother. Like the rest of Jimmy's cousins and aunts, she hates him for nearly destroying the town. She was completely horrified and fainted when Jimmy attacked Baby Eddie. When she woke up, she was shocked to discover her baby speaking adult speak. She reconciles with Jimmy and apologizes to him and his parents for little Eddie trying to destroy them all. However Jimmy comments: If I were you, Aunt Kari, I'd keep a leash on him. Seen in the episode Clash of the Cousins. She is voiced by Tress MacNeille

• April The Gorlock has had one appearance on the show in the episode "Win, Lose, or Kaboom". In fear of her planet's safety, she had performed a seal of trust with Jimmy which resembled a kiss. Cindy had observed this and was jealous. Jimmy's hormones had kicked in after that, and he had hoped for another kiss from her when the adventure was over. He and April would send messages via space rock after that. Her real name is Chee Aaaaaaaaaah Doik!, but she hates this name and threatens anyone who calls her by it. Voiced by Alyssa Milano.

• Arnie an orange haired Scots-Irish American wealthy child who is Nick's best friend. He is mostly seen in the background. He scared the children half to death on the planet they were on as part of Nick's plan. Recently, he has become Butch's bully dummy. In The Egg-pire Strikes Back he got a home tattooing kit from the Yolkians. Voiced by Rob Paulson

B

• Baby Edward "Eddie" Neutron, Jimmy's infant evil genius cousin, whom looks identical to Granny Neutron as an infant. He put in bombs on the gift & on the birthday cake to kill the family and have their money. According to himself, Eddie is a lot smarter than Jimmy and he's only 17½ months old ("Wait 'til I hit puberty! Ba bing!") Eddie is voiced by Mark DeCarlo. (Appears in Clash of the Cousins, and The League of Villains).
• Beautiful Gorgeous, an evil villainess whom is the daughter of Jimmy's enemy, Professor Calamitous. Her childhood dream was to become the person who 'puts those little plastic things on the ends of shoelaces'. She hypnotised and nearly married her arch enemy Jet Fusian She is voiced by Wendie Malick. (Appears in Operation: Rescue Jet Fusion, My Big Fat Spy Wedding, and The League of Villains).She was a playable character in the video game "SpongeBob SquarePants featuring Nicktoons: Globs of Doom".
• Betty Quinlan, Was Jimmy's first crush. She is nice to him, and can make him do things he normally wouldn't do (unintentionally of course). Betty told Cindy that she's fully aware of Jimmy and Cindy's feelings for each other, and to "Just relax and keep out of my face. He's all yours". (Appears in Party at Neutron's, Out Darn Spotlight, One of Us, The Vanishing Act, and brief appearances on My Big Fat Spy Wedding, Attack of the Twonkies and The Jimmy Timmy Power Hour 2: When Nerds Collide). Betty is voiced by Kath Soucie.
• Bolbi Stroganovsky, also known as the "boy from fairy-tale land" or the "boy with the funny name", is the weird resident exchange student from Backhairistan. He normally speaks broken English, but has a surprisingly good Shakespearean acting voice (but only when auditioning). He is voiced by Phil LaMarr. He appears as a medieval peasant and speaks in a vaguely Russian/Czech accent, and went with Jimmy, Carl, Sheen, Cindy, and Libby to the game show in Win, Lose, and Kaboom (by accident) and was even considered from a Species Unknown by the production staff of the game show. He voted himself off of the team in a Survivor-esque squence, thinking he was going to win a prize. He states that "Super-Kaboby Man" is the most famous hero of Backhairistan. It is known that he has a blond sister who looks just like him in Crouching Jimmy, Hidden Sheen.
• Bonzilla, a 10 inch tall reptilian beast in Japan. Bonzilla is a spoof of Godzilla, Bonsai style. He makes two appearances, one in Retroville 9, and one in Win, Lose and Kaboom. In Retroville 9, he is visited by the Retroville 9 after losing to another team in Japan. Sheen insults Bonzilla, resulting in him being burned into a crisp by Bonzilla's fire breath. In Win, Lose and Kaboom Bonzilla is a member of the audience. In the movie he is a lot bigger.
• Britney Tenelli, An Italian American friend of Cindy & Libby, who is also a back up dancer with them. She wears a pink and white tank top with her navel exposed, a pink jacket, pink pants, and light brown shoes. Her hair is braided in pigtails and her eyes are bluish gray. Britney's character is most likely meant to be a parody of pop star, Britney Spears. Britney usually appears as a background character but occasionally hangs around with Cindy and Libby. Britney is voiced by Candi Milo.
• Brobot, Jimmy's annoying, robotic brother who lives on the moon with robotic parents Jimmy made to get rid of him. Although Brobot irritates Jimmy, it is shown that Jimmy cares about Brobot (when Jimmy disconnects him, he cries "What have I done?") Voiced by Paul Greenberg. (Appears in episodes Brobot, The Junkman Cometh, The League of Villains).
• Brains, One of four participating groups on Intergalactic Showdown. They have no bodies, (yet still somehow manage to talk), and are motile only by moving their brain stalks as feet, which makes them extremely slow. To make up for this, they possess extremely advanced telepathy and hypnosis powers, which usually render their opponents helpless. As one might guess, they usually win challenges by the use of skill and logic, rather than strength.
• Buford Lee Stormshuckle, the Southern American warden of a correctional facility who framed Jimmy for a bank heist. He taunts Jimmy by pseudo-offering him a glass of ice cold lemonade. When Sheen and Carl unsuccessfully tried to free Jimmy, he arrested them too. However, Jimmy and his friends blinded him while trying to escape. He looks in Retroville for them near Cindy Vortex's house with his boom box (apparently budget cuts made it so that he could only afford a recording of dog barking instead of a real search dog). Jimmy, Sheen, and Carl sneak into Cindy's house after there was a reward for 10,000 dollars which she had to call 555-55555555. Cindy was definitely going to turn them in, claiming there was a lot she could do for $10,000. Sheen commented: I'd start with your room. Have you considered glow in the dark Ultralord wallpaper. The guys are caught by Buford, however thanks to Sheen's hyperactive behavior, the Warden confesses by saying: I think I'll give you a dollar just to shut your trap.. After Jimmy proved to the police Stormshuckle was the real bank robber, Stormshuckle was fired and arrested. He is voiced by Bill Farmer (appears in Who Framed Jimmy Neutron?).
• Burp Boy, Carl's superhero form. His power is that his burps are sonic (voiced by Rob Paulsen). (Appears in The 'N' Men).
• Butch Pakovski, the slightly slack jawed Polish American bully who fears big words, voiced by Rob Paulsen. Butch has a little brother. Butch may have a softer side as his clearing his anger with stacking sticks in the episode Who's Your Mommy. In the beginning of the episode Jimmy Goes To College, Jimmy says big words about his unstable molecules and Butch holds his head, saying, "Big words! They hurt! They hurt!"
• Blix, Eustace Strytch's assistant, who always keeps him company. When Eustace Strytch is upset, Blix lets him kick his butt. Blix has a big nose, bushy gray eyebrows, a black suit, and light gray hair. He is British in Billion Dollar Boy, but he is German in King of Mars. (Appears in the episodes Billion Dollar Boy, King of Mars, My Big Fat Spy Wedding, Win, Lose, or Kaboom!, Aauggh! Wilderness, a cameo in Best in Show, Grumpy Young Men, Who Framed Jimmy Neutron?, and The Jimmy Timmy Power Hour 3: The Jerkinators.) He is voiced by Billy West.

C

• Carl Sheenster, Jet Fusion's fitness instructor, mentioned in Operation: Rescue Jet Fusion. More than likely a pun as his name is a portmanteau of Carl and Sheen
• Carlman, a boy who once owed Sheen 2 dollars and 36 cents, he's similar to Nick. (Appears in the episode Attack of the Twonkies)
• Cap'n Betty, an odd sailor who knows about a monster that Jimmy is trying to reveal to be false. He is voiced by Jim Cummings. (Appears in episode Monster Hunt, My Big Fat Spy Wedding, and numerous cameos, many of them well-hidden).
• Chip, A teenage hologram of Skeet, used by Jimmy to fool his parents into thinking a camping trip is supervised. He is voiced by Rob Paulsen. (Appears in episode A Beautiful Mine and makes various cameos throughout the show, such as in Best in Show).
• Chuck Lester, The short-lived Welsh American hall monitor who moved away to Greece. He was voiced by Crystal Scales (Appears in episode Hall Monster; Also is seen on Butch's team in the episode The Retroville 9).
• Coach Gruber, the coach of Lindbergh Elementary. He is voiced by Jim Belushi.
• Colonel McSwane, the head of the Atomic Monkey Special Forces Squad. Saved Carl and Sheen from captivity in My Big Fat Spy Wedding.
• Commander Baker an African American who is the Big Top Secret Organization commander. It is stated in My Big Fat Spy Wedding he did something illegal when he implanted a tracking chip inside Beautiful Gorgeous's head. He is also a at a constant upset by all the embarrassing pictures of him when he is showing Jimmy his mission. He is voiced by Michael Clarke Duncan (Appears in episode Operation: Rescue Jet Fusion, My Big Fat Spy Wedding).
• "Cool" Hugh, the cooler variation of Jimmy's father seen in the Father's Day episode. He was voiced by Mark DeCarlo.
• Corky Shimatzu, a famous Japanese big -shot TV programmer, whose catch-phrase is "Super Crazy!" with no relation to the professional wrestler. He is voiced by Billy West.
• Courtney Tyler, Britney, Libby and Cindy's Jamaican American friend; she is one of Jimmy's classmates. She usually appears in the background and is rarely mentioned in the show, although in the movie, she became a news reporter when all the adults were abducted. She has black hair and wears a purple shirt.

• Cousin Annabelle, Jimmy's paranoid, insane, and brown haired cousin. She suffers from many phobias. This was relevant when Carl touched and talked to her when she was sorting toothpicks. Jimmy also wishes some help for her shown by the comment: Carl: Your cousin's nice. Is she seeing anyone?. Jimmy: Hopefully a therapist. Seen in the episode Clash of the Cousins. She is voiced by Megan Cavanagh

• Cousin Gomer, Jimmy's other cousin besides Cousin Eddie, he sounds like Gomer Pyle from The Andy Griffith Show and Gomer Pyle, U.S.M.C.. He is extremely stupid and plays ping pong with a ball covered in saliva known as his spit ball. Cousin Eddie comments on how Jimmy is sometimes is dumb as him. He might have been completely oblivious when he was trapped or when Jimmy, Carl, and Sheen mistook him for the evil genius. Seen in Clash of The Cousins.

• "Crazy" Louie, mentioned in Stranded. Cindy would rather want Louie to be with her on the island because he can open coconuts with his tooth (until the ending of the episode when she'd rather be with Jimmy).

• Caterpillar a caterpillar from the first film. When Mrs Fowl gets shrunk by Jimmy's shrink ray, the Caterpillar tried to eat her, including while the Mom-and-Dad-are-gone-celebration. At the end he becomes Mrs. Fowl's pet.

D

• Dr. Dark/The Pizza Monster, A story-telling hologram gone awry, and the hologram and pizza hybrid that appears when Jimmy's sleepover machine goes haywire, Both voiced by Corey Burton. (Appears in episode Sleepless in Retroville).
• Dean Kane, dean of Pomona School of Advanced Physics, or SAP (his name is a parody of actor Dean Cain or less likely Dean Kamen). He was often distraught of Jimmy's invention wrecking the school. He even expelled him for streaking naked during Mrs. Moran's visit. However, he soon discovers Seymour was behind the unstable molecule attack. the Dean becomes eternally grateful to Jimmy. He also lets him and his friends throw a wild college dance party. appears in Jimmy Goes to College. He is voiced by Tom Kane
• Dr. Sydney Orville Moist, A paranoid dance-crazy scientist that works under water making algae men and then became Jimmy's enemy. Appeared in episode The Evil Beneath and was collaborated with Professor Calamitous in The Jimmy Timmy Power Hour 2: When Nerds Collide briefly before being betrayed and ejected. He is voiced by Jeff Bennett.

E

• Emily Svalsbord, a Norwegian American redheaded bespectacled appears in the background often, in the episode Love Potion #976\j she told her boyfriend Oleander how to make a greeting card for her (although Oleander's supposed to surprise her) (Voiced by Debi Derryberry).
• Elves, Santa Claus's elves. They make toys for all the little good children of the world. They were very angry with Jimmy after his machine broke Santa. All are voiced by Jeffrey Garcia. (Appears in episode Holly Jolly Jimmy).
• Elke Elkberg, Carl's gorgeous pen pal from Sweden. She originally was supposed to be a really famous person, but confess to only being a nerd. She and Carl share an unhealthy love of llamas and start dating. Only seen in Carl Wheezer: Boy Genius. She is voiced by Grey Delisle
• Mr. Estevez, Sheen's elusive father, voiced by Carlos Alazraqui.
• Eunice Willoughby, Principal Willoughby's sister. A picture of her appeared at the end of Hall Monitor, dressed as Albert Einstein. She was a hall monitor once.
• Eustace Strytch, a rich, snobby kid seen in Billion Dollar Boy, King of Mars, The League of Villains, The Jimmy Timmy Power Hour 3: The Jerkinators, and a cameo appearance in "Attack of the Twonkies". He is the bitter rival of Jimmy, and has an extremely annoying laugh. Voiced by Rob Paulsen.
• Ernest Abercrombie, the military general. Not as smart as he looks. Appeared in N-Men, and Substitute Creature. He is voiced by Ernest Borgnine.
• Evil Jimmy, voiced by Rob Paulsen, is Jimmy's evil clone. He is created to do chores for Jimmy, though he causes trouble and escapes instead. He later makes prank calls all over the Earth after hijacking the communication satellite. Jimmy eventually attempts to turn Evil Jimmy good, though he fails, and Evil Jimmy just pretends until he is able to use the duplication machine in order to create a whole new evil planet. The cause is revealed to be a dark chip placed in the machine, which is destroyed, causing the planet and evil Jimmy to disappear.
• Evil Carl, a bully-like version of Carl from Evil Jimmy's dark version of Earth.
• Evil Sheen, an evil version of Sheen from Evil Jimmy's dark version of Earth, as a counter to Sheen he is obsessed with Robo-Fiend
• Evil Cindy and Libby, Two evil versions of Cindy and Libby, from Evil Jimmy's evil Earth, they are only seen giving an Alt. nicer version of Nick a wedgie, and then electricuted by their own gadget.

F

• Flippy, Hugh's dummy and a semi-villain. He was used as firewood to ward of the Twonkies in Attack of the Twonkies. He is a parody of Slappy the Dummy from Goosebumps. (Appears in Attack of the Townkies and Flippy.)
• Florgas, a giant robotic creature that resembles a flying ant. They were used in various challenges throughout the Intergalactic Showdown. Carl, who was at first extremely afraid of them, later managed to tame his Florgas, whom he named "Sugarcube", at the end of the show when Jimmy and company saved the Gorlocks from planet destruction.
• Future Copbot, a robot from an alternate future with four arms that loves Grey Star music and works for Libby. He has the ability to clone himself. Voiced by Tom Kenny. (appears in episode The Tomorrow Boys)
• Mr. Folfax, Libby's father, appears in the episode Make Room For Daddy-O. He's similar to Mr. Estevez.
• Mrs. Folfax, Libby's mother, appeared in Journey to the Center of Carl. She is seen trying to cure Libby from Jimmy's sick patch by placing a wasp in a cup on her forehead. voiced by Crystal Scales.

G

• Mr. Giggles the Clown, the deadpan voiced clown (who ends up doing boring tricks if he runs out) seen in the Hypno Birthday To You and Foul Bull, voiced by Ben Stein. Also makes a cameo in "Sheen's Brain" in the costume shop's window.
• Granny Neutron, Hugh's mother and Jimmy's grandmother. Jimmy once turned her into a baby in Granny Baby, voiced by Phyllis Diller.
• Grandma Taters, a sweet-seeming old lady who is actually a hostile alien. Tried to turn the citizens of Retroville into cheerful zombies via hypnosis. Featured in One of Us and The League of Villains, voiced by Edie McClurg. Makes a cameo appearance in Best In Show.
• Graystar, Libby's favorite band. They appear as college students in Jimmy Goes to College, and they also have a cameo appearance in the episode The "Incredible Shrinking Town". They are seen in the background as Butch and Nick are picking for basketball team members at the beginning. The Future Cop-bot is a huge fan of theirs. (Appear in Attack of the Twonkies, The Tomorrow Boys, Jimmy Goes to College, and The Incredible Shrinking Town). They are an existing indie band from Albany, New York currently under the name "The Day Was Mine."
• Germ a T4 phage bacteria that made an appearance in Journey to the Center of Carl and made a cameo in Win, Lose and Kaboom!.
• Gorlock, a race of alien creatures that have green skin and tusks, and who usually win challenges with the use of brute strength and force. They belong to one of four participating groups on Intergalactic Showdown. Most likely the youngest of them, April, (which she prefers to be called in place of her extremely long alien name), befriends Jimmy Neutron, with whom she eventually shares the Gorlockian Seal of Trust, much to the dismay of Cindy. At the end of the show, their planet was to be destroyed, (as they were the losing team), before Jimmy and company stopped the detonation countdown and shut down the show for good. At the end she kisses him again, stating this time it was a "kiss". It appear she started to have feelings for Jimmy but she was never seen again in future episodes.

H

• Hank McSpanky, the founder of a chain of fast food restaurants, aptly named, McSpanky's. It is said that he is Scottish and once met Jimmy's father, whom he almost went into business with.
• Hilgo, the big, fearsome Russian American maid that can only say one word---Да "Da" (Russian for yes) ---and was seen in Time Is Money she also made a guest appearance in Return of the Nanobots as a lunch lady who once made shoes for lunch, voiced by Jill Talley.
• Humphrey, Cindy Vortex's dog seen in many episodes usually accompanying her. Cindy says Humphrey is the best dog in Retroville.
• Hulk Jimmy, Jimmy's orange-skinned, green-haired-and-eyed, Hulk-like form with freakishly impossible strength and the ability to heal himself, voiced by Dan Castellaneta.

I

• Ike Wolvermein, One of Jimmy's African American classmates, he is one of the cool kids in Lindberg Elementary School. He usually can be seen in the background. He once had a slumber party, which Sheen used as blackmail to get Carl to vote for him. Ike has a father who owns a bank and a 5 star restaurant, making him very rich. He also lives in a very large mansion with over 70 rooms. His father and him were one of the cheaters by the comment: Mr. Wolvermein: played fair. Crowd: Yay!! Mr. Wolvermein: Then cheated. Crowd: Boo!(Voiced by Crystal Scales) (his father is voiced by Tom Kenny)
• Ignishka Stroganovski, Bolbi's sister. She looks very much like Bolbi, except she wears a dress and she has blonde hair with 2 long pigtails. She is seen doing a duet to Bolbi's "Slap, Slap, Slap, Clap, Clap, Clap" song and dance.
• Invisible Sister, Libby's superhero form, her power is to turn invisible and project force fields, voiced by Crystal Scales. Her powers may be based on Violet from The Incredibles or The Invisible Woman in The Fantastic Four. (appears in The 'N' Men)

J

• Jet Fusion, Jimmy, Carl, and Sheen's (2nd) favorite superhero. A parody of James Bond ("bond" and "fusion" mean the same thing). He is voiced by Christian Slater. (Appears in episode Operation: Rescue Jet Fusion, My Big Fat Spy Wedding).
• Jimmy Clones: Happy, Gloomy, Funny, Cool, Romantic, and Evil, Clones of Jimmy. All voiced by Rob Paulsen and Jeff Bennett. In Send In The Clones, Jimmy made these clones to do his chores while he harvested moon rocks. Jimmy's clones caused trouble, and he had to stop them, but the Evil Jimmy got away. In this episode, there is a reference to the Quentin Tarantino film Reservoir Dogs, seen when the clones are walking down the street the way the Mr.'s Pink, Blue, Orange etc. did, along with a tune similar to "Little Green Bag". In The Trouble with Clones, Evil Jimmy came back, and started hypnotizing people when Jimmy tried to turn him good and hired him to do the chores. Evil Jimmy then made an evil clone of the Earth, causing the real Earth to disappear. The original Jimmy went to that Earth and had to reverse the effects. In the end, the real Earth is saved, and the cloned Earth, along with Evil Jimmy, were sucked into the Dark Matter Dimension. All of the clones are possibly deceased, although Evil Jimmy vowed to return.
• Ms. Jingle Bells (Megan Cavanagh; appears in episode Operation: Rescue Jet Fusion). A girl rescued by Jet. A parody of various Bond girls.
• Junkman (Charlie Adler; appears in episode The Junkman Cometh, The League of Villains and makes a cameo in The Best In The Show as a contestant, and Win, Lose and Kaboom), a filthy creature from another planet. Deals in fixing up and selling refuse products throughout the galaxy - "you trash it, I cash it!".It is possible he is still in the Late Cretaceous period.

K

• King Goobot V, the Yokian King; appears in the feature film, The Eggpire Strikes Back and League of Villains. He had his armada kidnap all the parents in Retroville and attempted to scarfice them to the Yokian god, Poultra, a giant monstrous chicken. He was stopped by Jimmy and all the other kids. It is possible he is still in the Late Cretaceous period. He serves as the main antagonist in the film. He is voiced by S. Scott Bullock (Patrick Stewart in the film).

L

• Lance (Billy West; appears in episode The Retroville 9).
• Lars Svenson (Billy West; appears in episode The Science Fair Affair). Important Swedish scientist Hugh contacted for Jimmy after he was banned from the science fair. He almost gives Jimmy the Nobel Peace Prize for his 'I Can't Believe It's Not Oil', but after he is almost turned into mulch, he changes his mind.
• Libby's little brother The legs in Libby and Mr. Folfax's magic trick. (Crystal Scales; appears in episode Make Room for Daddy-O).
• Living Lima bean Appears in I dream of Jimmy and made a cameo in Win Lose and Kaboom
• Louis "Lou" (Billy West; appears in episode Holly Jolly Jimmy).
• Lucky Joseph "Joe", has an eyepatch and owns Lucky Joe's Cleaners. (Billy West; appears in episode When Pants Attack, and appeared as the bus driver in the film).
• Leppy", A Leptictidium he only appeared in Sorry, Wrong Era he was Carl's prehistoric friend. (his species lived in the Eocene not the Cretaceous)

M

• Malcolm X appears in episode Operation: Rescue Jet Fusion
• Maggie (Crystal Scales; appears in episode Birth of a Salesman).
• Masseuses (Megan Cavanagh; appear in episode MaternoTron Knows Best).
• MaternoTron, Jimmy temporary replacement robot Mom. (Megan Cavanagh; appears in episode MaternoTron Knows Best).
• Max, (Tom Kenny; appears in episode Maximum Hugh).
• Mayor of Retroville (Jim Cummings, later Tom Kenny; has a resemblance to Walt Disney and Clark Gable and later wears a top hat and a monocle; seldom appears).
• Meldar Prime, evil host of gameshow Intergalactic Showdown. Appears in Win, Lose and Kaboom Voiced by Tim Allen.
• Mayor Quadar (Mark DeCarlo; appears in episode "Normal Boy").
• Monks of Shangri-Llama, (appear in episodes Operation: Rescue Jet Fusion and Crouching Jimmy, Hidden Sheen).
• Mr. Wuggles, Carl's pet hamster (Appears in "My Son, The Hamster")
• Mrs. Moran, awarder of the Moran Grant. She dislikes Jimmy for appearing to her naked when she came to Pomona. She reconciles with him after she misjudges him and awards the coveted Moran Grant to the Pomona School of Advanced Psychics. She does miss her purse, though. After it vanishes into thin air by a molecule. appears in Jimmy Goes to College. She is voiced by Tress MacNeille
• Mummies (appear in episode Beach Party Mummy).
• Morgan Freeman, Sheen wished that he would be Morgan Freeman's best friend, but then Sheen is annoyed by him. (Appears in the episode Jimmy Timmy Power Hour 2: When Nerds Collide). (Voiced by Kevin Michael Richardson).
• Miss Winifred Fowl, (Andrea Martin) Jimmy's teacher

N

• Nanobots (Daran Norris (orange, large) and Tom Kenny (red, thin); appear in episode Safety First, Return of the Nanobots, and Fundemonium). Attempt to "please" their creator, Jimmy. They don't usually get along. The Nanobots saucer module is actually an allusion to the saucer module in the movie "Batteries Not Included".
• Nathan Decarlo an Italian American boy who is cheating at the Picnic Games in episode Maximum High (Jeffrey Garcia; seldom appears).
• Needleheads, a race of alien creatures from an unknown planet that most closely resemble a giant worm with three legs and a pointy head. They can only say one word, "Mibs", and otherwise express themselves through body language. They belong to one of four participating groups on Intergalactic Showdown.

• Newton "Newt", Jimmy's uncle and a seemingly, mild-mannered, semi middle aged man who is Eddie's father. Like Jimmy's other cousins and aunts, he hates Jimmy for nearly destroying the town, most noticeably when he said: Or those evil rotten aliens. He has black-brown hair and more than likely reconciled with Jimmy after discovering it was Baby Eddie who tried to kill him and the others. Only appears in Clash of the Cousins He has a striking appearance to John A. Davis, the shows creator.

• Nissa (Debi Derryberry; seldom appears). A girl with a single buck tooth that taunted Jimmy once. She also loves jump rope. It is stated that she is Greek American. Her appearance is blonde, a yellow shirt, blue pants and a surprisingly light complexion for a Mediterranean

O

• Octopus Man, a movie monster ("he has 8 arms!") (Mark DeCarlo; appears in episode Nightmare in Retroville as a monster in a movie that Hugh was watching).
• Officer Tubbs (Frank Welker; appears in episode Jimmy On Ice, Professor Calamitous, I Presume,Holly Jolly Jimmy, and Who Framed Jimmy Neutron).
• Old Lady Nussbaum (Megan Cavanagh; appears in episode Normal BoyWas mentioned in lady sings the news).
• Oleander Svalsbord, a Norwegian American odd geek bullied by Butch, and once owed Sheen 53 cents (Rob Paulsen; seldom appears)
• Ooblar, Yolkian sidekick of King Goobot (in the original film by Martin Short, in the series by Paul Greenberg). No longer Goobot's assistant because in the League of Villains, Goobot said he was traded for sulfur butter.
• Ozzie (Crystal Scales; appears in episode The Retroville 9).
• Oreaso Dean (mentioned, never appeared); Oreaso is Nick's extremely rich father, CEO of Dean Industries.

P

• Phantom, (Frank Welker; appears in episode Phantom of Retroland) A mysterious ghost that is rumored to haunt Retroland by night. He resembles the Grim Reaper, has a salami for a right leg, and is said to eat people wandering the park while he is haunting. From the beginning to near end of the episode, it is assumed that the Phantom does not exist. However, at the very end it is revealed that the Phantom is real.
• Popbot (Jim Cummings; appears in episode Brobot and The Junkman Cometh), Brobot's father robot.
• Poultra, original chicken goddess of Yolkian race (only appears in original movie and in The Eggpire Strikes Back)
• Principal Willoughby, The flamboyant, Broadway-loving Principal at Lindbergh Elementary School. He is also quite fat. He directed Macbeth in Space and was extremely giddy about it. He shows fierce anger when one of his shows are ruined. However, he is a truly good person, albeit forgetful at times. He is energetic, enthusiastic, and over the top and seems to be everything a good elementary school principal should be. He is approachable, kind, and has a gentle nature to him...not to mention that he's fairly clueless when it comes to most aspects of life. Despite this, he seems to have a knack for his chosen profession. He seems to genuinely care about his scholars, and has clearly taken the time to get to know each and every one. He has a sister named Eunice who looks like Albert Einstein, and comments on always getting then confused. (He is voiced by Rob Paulsen; appears a handful of times.)
• Princess Guan Qi "Peggy" Tsu (Ming-Na; appears in episode The Great Egg Heist. She is really Professor Calamitous in disguise). Also appears in the background of "My Big Fat Spy Wedding".
• Professor Crank (Dan Castellaneta; appears in episode Operation: Rescue Jet Fusion)
• Professor Finbarr Calamitous, (Tim Curry; appears in episodes Professor Calamitous, I Presume, The Great Egg Heist, Operation: Rescue Jet Fusion, Lights! Camera! Danger!, My Big Fat Spy Wedding, The League of Villains and The Jimmy Timmy Power Hour 2: When Nerds Collide). Ms. Fowl's former student, despite his age and Beautiful Gorgeous's father. He is Jimmy's arch-nemesis and the show's most recurring antagonist. Finbarr Calamitous was once a brilliant boy who could never finish anything, not even a sentence. The only he could finish was a robotic suit, though he didn't consider it finished since he didn't put a bathroom into it. He later overcomes this to some extent, and Finbarr Calamitous is heard completing sentences as seen in Operation: Rescue Jet Fusion, The Great Egg Heist, and The Jimmy Timmy Power Hour 2: When Nerds Collide. However, he still has a habit of not finishing his plans, or more specifically, he is able to carry out his plans but does not plan on what he is going to do after that. He has also been the main antagonist in Nicktoons Unite! and Nicktoons: Attack of the Toybots where he faced (beside Jimmy Neutron & Timmy Turner) Danny Phantom, SpongeBob SquarePants and other Nicktoon heroes.
• Pteranodon, The pterosaur that appeared in the episodes Sorry, Wrong Era, and The League of Villains. It took Sheen in Sorry, Wrong Era. (in its appearances it was identified as Pterodactyl)

Q

• Queen Hasabataslapya, a fictional Egyptian queen said to be an ancestor of Libby, her name is a pun on "how's about I slap ya"?
• Quentin Smithee, a movie director who is an obvious parody of Quentin Tarantino. His name is also a reference to Alan Smithee, a pseudonym used by directors who wish to distance themselves from a film. He is later revealed to be Professor Calamitous in disguise. Even though the character was devised by Calamitous, a person who looks just like him can be seen in the church in the episode My Big Fat Spy Wedding

R

• Rayburn, the holographic butler (servant) (Corey Burton; appears in episode Aaughh!! Wilderness!!) Hugh touched the holographic butler, trying to figure what it was all about, which eventually leads up to a chain of events leading to the explosion of the device. Rayburn also appears in "Win Lose And Kaboom!" as a real person and can be seen when Carl takes his picture in front of the giant space rock. He was also seen in "The Jimmy-Timmy Power Hour III" as Cindy's family butler and in "Gumpy Young man" as a cameo (not hologram).
• Robo-Fiend, Lactose-intolerant enemy of Ultralord (Rob Paulsen; appears in episode Ultra Sheen, mentioned often by Sheen)
• Roxy, the Junkman's alien dog that looks like a French Poodle and is Goddard's crush. Appears in episodes, The Junkman Cometh and League of Villains. It is possible she is still in the Late Cretaceous period.

S

• Sagebrush Sally a very beautiful Texan cowgirl who is an expert at rodeo and horse racing. Jimmy, Carl, and Sheen were infatuated with her. They all tried to impress her by doing rodeo stunts. (Carl tried to wrestle pigs, Sheen tried to wrangle horses, and Jimmy tried to ride a bull.) Jimmy won Sally over with his stunt. When Sheen got on the wrong bull, Sally was worried and told Jimmy to get on Back Breaker, the only horse fast enough. After Miss Fowl saved Sheen and a magnet got the better of Jimmy, Sally saw the ruse and was disappointed in him. She is last seen talking to Cindy and Libby about the nerve of some boys. (Grey Delisle; appears in episode Foul Bull).
• Santa Claus (Mel Brooks; appears in Holly Jolly Jimmy), the famous holiday figure who is a genius like Jimmy Neutron is. He was crippled due to Jimmy's machine. He stated Jimmy was on his naughty list for some time.
• Sasha Vortex, Cindy's mother. A beautiful woman born in France. She has high standards for Cindy and expects Cindy to follow in her footsteps. She is an accountant. Cindy's mother loves French food. She is fair friends with the parents of the other kids. She is voiced by Tress MacNeille.
• Susie Vortex, Cindy's aunt, award-winning athlete (Megan Cavanagh; appears in episode Maximum Hugh). Although her name suggests that she is Cindy's paternal aunt she actually bears a striking resemblance to Cindy's mother. She once impersonated Cindy's mother at a field day so Cindy could cheat to win, but Jimmy figured out the truth when he noticed "Sasha" having a slightly different height, different eye color and a zipper on the back of her neck.
• Seymour Flimelflarb The "Official Smart Guy on Campus" at Pomona Tech. He is in the episode Jimmy Goes To College.
• Sheezicks, (Mark DeCarlo; appears in episode Maximum Hugh)
• Shmengo, an alien that resembles an enlarged jellyfish and has the ability to discharge electrical pulses on whomever it touches. Shmengo was born when Carl became "pregnant", and was later named by him as well. Shmengo left Earth with his parent, (presumably his mother), immediately after being born, and went back to his home planet, where he was later visited by Jimmy, Carl, and Sheen for his birthday celebration.
• Shirley, a villain created by Jimmy Neutron and Timmy Turner (only appears in TV movie Jimmy Timmy Power Hour 3). Although he is the main villain of the movie, he acts humble, polite and even is dimwitted. It is only when Jimmy and Timmy abandon him at a mall that makes him turn evil.
• Skeet, Calls everyone "dude" and is the employee of the month at the McSpanky's fast food restaurant. (Rob Paulsen; appears in episode Men At Work) Skeet also is holographed in "A Beautiful Mine" as Chip the holographic bus driver. In "Best in the Show", he can be seen at the pet show with a pet monkey.
• Snappy, Carl's mutated turtle (appears in episode Monster Hunt)
• Special Girl, Cindy's super hero form, strength, flying, and super vision.
• Swimmy, Carl's undead goldfish (appears in episode Beach Party Mummy).
• Spamdini, The great, a magician that lost his hand and got it back, he hates tuna, he loves pastrami, he's a parody of the famous magician Harry Houdini. Spamdini lives in an alternate dimension, and although he could have gone back with Jimmy and his friends, he decides to stay where he is.(Voiced by Corey Burton) (Appears in the episode Vanishing Act).

T

• Tee (voiced by Kevin Michael Richardson) is one of the three alien claim-jumpers. He appears in episodes A Beautiful Mine, Men at Work, The Incredible Shrinking Town and The League of Villains. He is known to turn good in The League of Villains. He enjoys hugging, and dreams of opening a dress shop. Tee also hates it when people call him stupid, and says "Foo!" a lot. His name, action and personality are all an obvious parody of Mr. T. He acts rude and has a gangster personality, even up to his golden "T" necklace.He acts a lot like B.A. from the A Team

• Terry Finster (Candi Milo; appears in episode Safety First and can be seen in the oufield in Retroville 9).

• Tania Ann Zaloom - A girl who has black hair.

• T-Rex - This dinosaur is seen in Sorry, Wrong Era, The League of Villains, seen as a statue in the museum, and seen chasing kids in The Jimmy Timmy Power Hour.

• Thomas Edison (Rob Paulsen; appears in episode The Big Pinch).

• Tina Sue (Carolyn Lawrence; appears in episode Operation: Rescue Jet Fusion).

• Travoltron (Jeff Bennett; the second of three alien claim-jumpers, appears in episode A Beautiful Mine, Men at Work, The Incredible Shrinking Town and The League of Villains). His name was probably made by the fact that he sounds like John Travolta.

• Tremendous Jackson, baseball star and UltraLord expert (Kevin Michael Richardson; appears in episode The Retroville 9).

• Twonkie, a species of small puff ball-like aliens. One is found on a comet and multiplies and are kept as pets by the people of Retroville. They are similar to Gremlins in that they turn into monsters every time they hear music. They get put to sleep by Sheen's 'terrible singing'. If twonkies that have already heard music and turned into orange monsters go into a small space, they will turn into a huge, invincible monster that can only be subdued by Sheen's bad singing. Jimmy managed to capture most of them, but forgot Sheen's which quickly reproduced Asexually, followed by a "The end?" afterwards in the episode and video game, as a reoccurring gag, the twonkie's children are seen throughout the show but unnoticed by the characters, such as in a student's locker, in a chair at Jet Fusion's wedding, and behind Carl after he was being persecuted. Most of them were voiced by Frank Welker.

U

• Ultra Principal, the principal that Jimmy is sent to after touching Carl in Carl's dream version of Jimmy's school. This principal is actually a giant version of Sheen wearing his Ultralord mask. He sentences Jimmy to be Carl's "monkey boy" as a punishment for touching Carl.

• Ultralord, a superhero that Sheen is really obsessed with; he even made the Ultralord website. He has his own show (which is also named after him). His enemy is Robo-Fiend (voiced by Jim Cummings). Sheen has the hugest Ultralord collection and is offended when Nick or Cindy calls them "Dolls". Sheen, enraged, usually shouts that they are action figures. He was once tricked by Cindy in the first film into showing the class a rare, never-to-be-seen condition, Ultralord doll when Cindy asked how did Sheen know it was in the condition box. Sheen also met Ultralord in the first movie in Retroland, and gets an Ultra-mask from him. It is unknown of what happened to the Ultra-Mask, although it is possible that Sheen displayed it somewhere in his house.

V

• Vendanna – a robot and the lovely assistant of Meldar on Intergalactic Showdown. She often hosts many of the challenges and also gives away prizes to the challenge winners. Jimmy controls her to destroy the host. Her name is a play off of Vanna White of Wheel of Fortune.
• Vibrating Lad – Sheen's superhero form. His power allows him to vibrate his molecules at fast speeds, allowing him to run faster with the price of a weak bladder, though he later trains to overcome that weakness. (in episode "The 'N' Men").
• Mr. Vortex - Cindy's father. Appeared in episode Make Room for Daddy-O.
• VOX (Megan Cavanagh) – Jimmy's computer, rarely heard in later seasons.

W

• Ward Kimball appears in episode The Big Pinch'
• Wendell (voiced by Frank Welker; appears in episode Make Room for Daddy-O).
• Mr. and Mrs. Wheezer Carl's parents who are very over protective and share many of Carl's allergies and hypochondria (Rob Paulsen). In one episode Mr. Wheezer stated that he was allergic to ice; however, this would lead to an allergy to water.
• Willy Loman 3000, the ultimate sales robot (Tom Kenny; appears in episode Birth of a Salesman, named after Willy Loman of Death of a Salesman).
• Mr. Wuggles, Carl's hamster (Frank Welker; appears in episode My Son, the Hamster). Responds when Carl says "Wuggle Wuggle Wuggle".

Y

• Yentil Marvelstein (Debi Derryberry; appears in episode Journey to the Center of Carl) A sick child that joins Jimmy's classroom. She is more than likely Jewish American

• Yoo-Yee A skilled kung fu fighter who wishes to be The Chosen One. (he tried to defeat Sheen to gain this honor, but lost. He only appears in episode Crouching Jimmy, Hidden Sheen). He is voiced by James Sie.

• Yuri, Bolbi's pet skata goat who's skilled at music; It appears in Best in the Show.

Z

• Zix, (Maurice LaMarche; leader of Tee and Travoltron, appears in episode A Beautiful Mine, Men at Work, The Incredible Shrinking Town and The League of Villains). He appears to be based on comedian Jon Lovitz.