John Cusack

Igor (voice)

Myleene Klass

Dr. Holzwurm (voice)

Robin Walsh

Dr. Holzwurm's Igor (voice)

Matt McKenna

Dr. Herzschlag (voice)

John Cleese

Dr. Glickenstein (voice)

Steve Buscemi

Scamper (voice)

Sean Hayes

Brain (voice)

Eddie Izzard

Dr. Schadenfreude (voice)

Jay Leno

King Malbert (voice)

Jennifer Coolidge

Jaclyn / Heidi (voice)

Molly Shannon

Eva (voice)

James Lipton

Himself