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
Christian Slater
Dr. Schadenfreude's Igor (voice)
Arsenio Hall
Carl Cristall (voice)
Jess Harnell
Announcer / Royal Guard #2 (voice)
Zoë Bright
Blind Woman / Killiseum Fan #1 (voice)
Sophia Eraklis
Blind Orphan #1 (voice)
A. Cheron Hall
Blind Orphan #2 / Blind Orphan #4 (voice)
Alexander Leondis
Blind Orphan #3 (voice)
Michael Leondis
Blind Orphan #6 (voice)
Nicole Leondis
Blind Orphan #7 (voice)
Juliana Leondis
Blind Orphan #5 (voice)
Robin Tisserand
Blind Orphan #8 (voice)
Paul Vogt
Buzz Offmann (voice)
Frank Welker
Animals' vocal effects (voice) (uncredited)