Jason Lee
Shoeshine / Underdog (voice)
Jim Belushi
Dan Unger
John Slattery
Mayor
Peter Dinklage
Dr. Simon Barsinister
Brad Garrett
Riff Raff (voice)
Taylor Momsen
Molly
Amy Adams
Polly Purebred (voice)
Alex Neuberger
Jack Unger
Larry Vigus
Security Guard
Bates Wilder
Cop
Frank Ridley
Police Sergeant
Alexander 'Alex' Garde
Small Boy
Diana Shneider
Police Secretary
Samantha Bee
Principal
John Franchi
Observer
Ezra Buzzington
Referee
Jay Leno
Jay Leno
Susie Castillo
Diana Flores
Phil Morris
Supershep 1 (voice)
Michael Massee
Supershep 2 (voice)
Cam Clarke
Little Brown Dog / Supershep 3 (voice)
John DiMaggio
Bulldog / Supershep 4 (voice)
Danny Mastrogiorgio
Crazy Dog (voice)
Jess Harnell
Astronaut (voice)
Susan Garfield
Office Worker
Timothy Crowe
Police Chief