 Ralph Macchio17 Year Old Tim (voice) | 17 Year Old Tim (voice) |
 Eric IdleEvil Martin (voice) | Evil Martin (voice) |
 Hynden WalchJenny Mcbride (voice) | Jenny Mcbride (voice) |
 Harvey KormanFloyd (voice) | Floyd (voice) |
 Andrea MartinMuriel (voice) | Muriel (voice) |
 William H. MacyJustin (voice) | Justin (voice) |
 Dom DeLuiseJeremy (voice) | Jeremy (voice) |
 Peter MacNicolNarrator (voice) | Narrator (voice) |
| AAndrew Ducote10 Year Old Timmy (voice) | 10 Year Old Timmy (voice) |
 Arthur MaletMr. Ages (voice) | Mr. Ages (voice) |
 Doris RobertsAuntie Shrew (voice) | Auntie Shrew (voice) |
 Phillip Van DykeYoung Martin (voice) | Young Martin (voice) |
 Darleen CarrHelen (voice) | Helen (voice) |
| JJamie CroninTeresa (voice) | Teresa (voice) |
 Jameson ParkerTroy (voice) | Troy (voice) |
 Phillip GlasserReformed 19 Year old Martin (voice) | Reformed 19 Year old Martin (voice) |
| WWhitney Claire KaufmanCynthia (voice) | Cynthia (voice) |
 Steve MackallProfessor Valentine (voice) | Professor Valentine (voice) |
 Kevin Michael RichardsonBrutus (voice) | Brutus (voice) |
 Meshach TaylorCecil (voice) | Cecil (voice) |
 Debi Mae WestMrs. Jonathan Brisby (voice) | Mrs. Jonathan Brisby (voice) |
 Al JarreauThe Balladeer (voice) | The Balladeer (voice) |
 Bobbi PageThe 2nd Balladeer (voice) | The 2nd Balladeer (voice) |
| BBeth AndersenChorus (voice) (uncredited) | Chorus (voice) (uncredited) |
