The Adventures of Jimmy Neutron: Boy Genius - Jimmy's Nemeses

Jimmy's Nemeses

• Professor Finbar Calamitous: A recurring antagonist of the series. He is also one of Mrs. Fowl's past school pupils. Calamitous is a tiny, near-sighted, bald, short, eccentric, old, evil genius, who is one of the most brilliant and evil minds on the planet, and he'd be even more dangerous if he didn't have the bad habit of never finishing what he starts! Calamitous is determined to get Jimmy to finish his projects for him as he couldn't finish them himself. Calamitous was once a little boy, who could never finish anything (not even a sentence). He is voiced by Tim Curry.
• Beautiful Gorgeous (real name Georgia Calamitous): Professor Calamitous' daughter. She is an evil villainess. When Beautiful Gorgeous was a child, her dream was to become the person who puts "those little plastic things on the ends of shoelaces" (these are called aglets), though she could have been lying. Was a playable character in the video game "SpongeBob SquarePants featuring Nicktoons: Globs of Doom". She is voiced by Wendie Malick.
• King Goobot V: The main antagonist of the feature film Jimmy Neutron: Boy Genius and episodes The League of Villains and The Egg-pire Strikes Back. He tried to kill Jimmy and the town residents by feeding them to his god, Poultra, in the 2001 movie Jimmy Neutron: Boy Genius. He later tried to kill Jimmy by turning the residents against him and using Jimmy's DNA clone scanner to create a new Poultra and make Poultra eat the town residents. Later, he gathered with several of Jimmy's nemeses and was later deserted in the Cretaceous Period with the rest of the villains, menaced by a Tyrannosaurus Rex.
• Twonkies: An alien species from the comet Twonkus 3. They go through 3 stages of life. Each metamorphosis is triggered by music. The first stage is a small fuzzy cute creature. However when exposed to music they morph into mid sized monsters who destroy the source of music. The final stage is caused by the Twonkies forming together to complete one giant 8 foot monster. It is finally defeated when they realize that Sheen's singing voice is so bad it is recognized as anti-music to the monster and it falls asleep, allowing Jimmy to launch it back to the comet. However, Sheen's Twonkie remains un-morphed and produces more Twonkies. There is no longer a problem with them morphing, but the remaining few make cameos throughout the 3rd season including at the end of the last episode still not destroyed. Their voice effects are done by Frank Welker
• Eustace Strych: The richest boy in Retroville. Eustace was attracted to Cindy, but then used her as a means to get to Jimmy. He's voiced by Rob Paulsen
• Baby Eddie: Baby Edward (Eddie) Neutron was Jimmy's evil baby cousin, who has a grown man's voice when he talks in his normal voice, he then suddenly talks in a baby voice when surrounded by grownups saying, "Goo!". Eddie's only clothing is a diaper, and often holds a red swirly lollipop. He is only 17 1/2 months old. Eddie believes that he is a lot smarter than Jimmy. In "Clash of the Cousins", Eddie attempted to kill his family by putting bombs in a birthday cake to steal Aunt Amanda's fortune, but failed. He was voiced by Mark DeCarlo who also voices Jimmy's dad, Hugh. Paul Greenberg who did voice Brobot also voiced him by providing baby voice effects. Despite his intelligence and adult voice, he is still mentally immature as he is physically. He cries when upset, gets angry when Jimmy destroys his rattle, demands his sippy cup and always needs to be changed. He also appears in The League of Villains.