Peter Frampton

as Hugh Neutron (singing voice)

Mark DeCarlo

as Hugh Neutron / Mr. Vortex (voice)

Crystal Scales

as Libby Folfax / Libby's Brother (voice)

Billy West

as Sam Melnick / Corky Shimatzu (voice)

Frank Welker

as Goddard / Wendel / Special Vocal Effects (voice)

Candi Milo

as Nick Dean (voice)

Andrea Martin

as Ms. Fowl (voice)