Jimmy takes a journey to a far-off comet called Twonkus 3 and some adorable alien creatures called Twonkies follow him back to Earth in his sand samples. Carl gives them away as pets, despite Jimmy's warnings. When Jimmy finds out the Twonkies become dangerous monsters when exposed to music, he and his friends must round them up and send them back to space before it's too late.
Debi Derryberry
as Jimmy Neutron (voice)
Mark DeCarlo
as Hugh Neutron (voice)
Megan Cavanagh
as Judy / Vox 2000 (voice)
Rob Paulsen
as Carl / Mr. Wheezer / Butch (voice)
Jeffrey Garcia
as Sheen (voice) (as Jeff Garcia)
Carolyn Lawrence
as Cindy Vortex (voice)
Crystal Scales
as Libby (voice)
Andrea Martin
as Ms. Fowl (voice)
Billy West
as Sam / Louie (voice)
Candi Milo
as Nick (voice)
Jeffrey M. Gunn
as Nick's Singing Voice (as Jeff Gun)
Frank Welker
as Goddard / Twonkies (voice)
