 Debi DerryberryJames Isaac 'Jimmy' Neutron (voice) | James Isaac 'Jimmy' Neutron (voice) |
 Christian SlaterJet Fusion (voice) | Jet Fusion (voice) |
 Wendie MalickBeautiful Gorgeous (voice) | Beautiful Gorgeous (voice) |
 Michael Clarke DuncanCommander Baker (voice) | Commander Baker (voice) |
 Tim CurryProfessor Calamitous (voice) | Professor Calamitous (voice) |
 Dan CastellanetaProfessor Crank (voice) | Professor Crank (voice) |
 Frank WelkerGoddard (voice) | Goddard (voice) |
 Rob PaulsenCarl Wheezer / Monk / Voice / Clam (voice) | Carl Wheezer / Monk / Voice / Clam (voice) |
 Megan CavanaghJudy Neutron / Ms. Jingle Bells / Female Monk (voice) | Judy Neutron / Ms. Jingle Bells / Female Monk (voice) |
 Mark DeCarloHugh Neutron (voice) | Hugh Neutron (voice) |
 Jeffrey GarciaSheen Estevez (voice) | Sheen Estevez (voice) |
 Andrea MartinMs. Fowl (voice) | Ms. Fowl (voice) |
 Carolyn LawrenceCindy Vortex / Tina Sue (voice) | Cindy Vortex / Tina Sue (voice) |
 Crystal ScalesLibby Fallfax / Ike (voice) | Libby Fallfax / Ike (voice) |
 Kath SoucieBetty Quinlan (voice) | Betty Quinlan (voice) |
 Corey BurtonNarrator / Head Monk | Narrator / Head Monk |
 Ving RhamesChief (voice) | Chief (voice) |
