Team Neutron is the name of a team of crime-fighting preteens led by Jimmy Neutron. These friends often have adventures together and fight villains from all over the galaxy.
- Jimmy Neutron- the leader of the team and a 12 year old boy genius.
- Carl Wheezer- Jimmy's best friend, who loves llamas and is allergic to almost everything. He is the co-leader of the group.
- Sheen Estevez- Jimmy's other best friend who is very hyperactive and obsessed with a superhero named Ultra Lord. He is the brawn of the group.
- Cindy Vortex- Jimmy's arch-rival, female counterpart and girlfriend. She is the (secondary) brains of the group.
- Libby Folfax- Cindy's best friend and Sheen's girlfriend and female counterpart, who loves music and dancing and serves as a big sister figure to Jimmy. She is the group's voice of reason.
- Goddard- Jimmy's robot dog who does over a thousand things and is Jimmy's favorite out of all his inventions. He is the team mascot.
- Nick Dean- The most popular kid in Jimmy's class who is another one of his best friends and serves as a big brother figure towards him. He is the jock of the group.
- Hugh Neutron- Jimmy's slightly dim witted father, who loves ducks and pies. He is the clown of the group.
- Judy Neutron- Jimmy's housemother who often scolds Jimmy for his antics and mischief. She is the maid of the group.
- Brobot- Jimmy's robot brother, who is very annoying and always wants to play.
- Brittany Tenelli- Cindy's other best friend and Nick's girlfriend, who is often a third member of Cindy's friend group. She is the ditz of the group.
- Zix, Travoltron, and Tee- Former members of the League of Villains who joined Team Neutron after Sheen befriended Tee and Jimmy's friends saved Zix and Travoltron from a prehistoric snake.
- Bolbi Stroganovsky- An exchange student from Backhairistan who loves kabobs and slap-dancing.
- Betty Quinlan- Jimmy's crush, who he often tries to impress with his inventions.
- Elke Elkberg- Carl's female counterpart and pen pal from Sweden, who is a farm girl and loves llamas as much as Carl.
- April the Gorlock- A Gorlockian girl who the kids meet on Intergalactic Showdown and help shut down Meldar's evil system. She and Jimmy were temporarily interested in each other.
- The Brains- One of the species who competed on Intergalactic Showdown and helped the gang stop Meldar.
- The Needleheads- Another species who competed in Intergalactic Showdown and helped shut down Meldar's system.
- Timmy Turner- The main protagonist of The Fairly OddParents!, who team's up with the kids in the Jimmy Timmy Power Hour trilogy.
- Cosmo and Wanda- Timmys fairy godparents, who Jimmy used to think were holograms until the second crossover.