James Woods

as Gloomius Maximus (voice)

Kyle Fairlie

as Spaceboy / Young Dad (voice)

Joshua Tucci

as Billy Bevel (voice)

Kristen Bone

as Zowie (voice)

Cole Caplan

as Olie (voice)

Rob Smith

as Spot / Spacedog (voice)

Catherine Disher

as Mom / TV Journalist (voice)

Rebecca Brenner

as Pollie Pi (voice)

Noah Reid

as Screwy (voice)

Al Mukadam

as Wheelie (voice)

Len Carlson

as Pappy / TV Announcer (voice)

Adrian Truss

as Dad / Gizmo (voice)

Michael Cera

as Young Gizmo (voice)

Paul Haddad

as Willy Jollie (voice)

Juan Chioran

as Wally Jollie (voice)

Neil Crone

as Doctor Geary (voice)

Philip Williams

as Baxter (voice)

Ellen-Ray Hennessy

as Bonita (voice)

Sunday Muse

as Binky (voice)

Jake Goldsbie

as Junior Littlegreen (voice)

Richard Binsley

as Gene Littlegreen (voice)