Grey DeLisle

Mandy / Castigator (voice)

Greg Eagles

Grim / Sperg (voice)

Richard Steven Horvitz

Billy / Billy's Dad (voice)

Vanessa Marshall

Irwin / Mouse (voice)

Dee Bradley Baker

Alien Moonbeast / Alien Werewolf / Moonthing (voice)

Jeff Bennett

Alien #1 / Rat (voice)

Chris Cox

Meadowberry / Corporal / Postal Slob (voice)

Jennifer Hale

Billy's Mom / Stinky (voice)

Tom Kenny

Dr. Brainiac / Alien Pilot / Wiggly / Waiter (voice)

Mr. Lawrence

Alien #2 (voice)

Julian Stone

Sir Raven (voice)