John Cusack character Igor (voice)
Myleene Klass character Dr. Holzwurm (voice)
Robin Walsh character Dr. Holzwurm's Igor (voice)
Matt McKenna character Dr. Herzschlag (voice)
John Cleese character Dr. Glickenstein (voice)
Steve Buscemi character Scamper (voice)
Sean Hayes character Brain (voice)
Eddie Izzard character Dr. Schadenfreude (voice)
Jay Leno character King Malbert (voice)
Jennifer Coolidge character Jaclyn / Heidi (voice)
Molly Shannon character Eva (voice)
James Lipton character Himself
Christian Slater character Dr. Schadenfreude's Igor (voice)
Arsenio Hall character Carl Cristall (voice)
Jess Harnell character Announcer / Royal Guard #2 (voice)
Zoë Bright character Blind Woman / Killiseum Fan #1 (voice)
Sophia Eraklis character Blind Orphan #1 (voice)
A. Cheron Hall character Blind Orphan #2 / Blind Orphan #4 (voice)
Alexander Leondis character Blind Orphan #3 (voice)
Michael Leondis character Blind Orphan #6 (voice)
Nicole Leondis character Blind Orphan #7 (voice)
Juliana Leondis character Blind Orphan #5 (voice)
Robin Tisserand character Blind Orphan #8 (voice)
Paul Vogt character Buzz Offmann (voice)
Frank Welker character Animals' vocal effects (voice) (uncredited)
