Jim Cummings
Brain #2 / Mayor Quadar (voice)
Tim Allen
Meldar Prime (voice)
Grey DeLisle
Vendanna (voice)
Frank Welker
Goddard (voice)
Billy West
Sam / Corky Shumatsu (voice)
Alyssa Milano
April (voice)
Phil LaMarr
Bolbi Stroganofsky / British Tourist (voice)
Jeff Bennett
Gorlock #2 / Brain #1 (voice)
Rob Paulsen
Carl Wheezer/Mr. Wheezer/Mrs. Wheezer/Test Pilot/Announcer (voice)
Megan Cavanagh
Judy Neutron / Mrs. Vortex (voice)
Jeffrey Garcia
Sheen Estevez / Army Guard (voice)
Carlos Alazraqui
Sr. Estevez (voice)
Mark DeCarlo
Hugh Neutron / Emergency System / Gen. Abercrombie (voice)
Debi Derryberry
Jimmy Neutron / Alien Actress / Alien Woman (voice)
Carolyn Lawrence
Cindy Vortex (voice)
Jess Harnell
Meldar Prime (singing voice)
Crystal Scales
Libby Folfax (voice)
Joe Lala
Sr. Estevez (voice)