Richard Steven Horvitz

as Billy / Billybot / Harold / Pale Ghoulish Juror / Chippy the Squirrel (voice) (as Richard Horvitz)

Grey DeLisle

as Mandy / Mandroid / Older Mandy / Milkshakes / Some Kid (voice)

Greg Eagles

as Grim / Sperg / Pirate #6

Vanessa Marshall

as Irwin / Pirate #5 / Unicorn (voice)

Maxwell Atoms

as I'll Cut You Guy / Pirate #2 / Horrorbot / Burnt Skeleton Guard (voice)

George Ball

as Peequay (voice)

Jane Carr

as Bride of Frankenstein (voice)

Greg Ellis

as Creeper / Horror's Hand / Pirate #3 / Paperboy (voice)

Bart Flynn

as Giant Cyclops / Ugly Pirate (voice)

C.H. Greenblatt

as Fred Fredburger / Pirate #4 (voice)

Jennifer Hale

as Billy's Mom (voice)

Dorian Harewood

as Older Irwin (voice)

Phil LaMarr

as Space Villain / Glacier of Evil / Dracula / Judge Roy Spleen / Underworld Cop (voice)

Rachael MacFarlane

as 2 Headed Parrot (voice)

George Segal

as Horror (voice)

Armin Shimerman

as General Skarr / Pirate #7 (voice)

James Silverman

as Executioner / Pirate #1 (voice)

Lauren Tom

as Numbuh Three (voice)

Billy West

as Pirate #8 / Miniature Cyclops / Spider Clown Mailman / Beast Master (voice)

Fred Willard

as The Boogey Man (voice)