Jason Lee as Shoeshine / Underdog (voice)

Peter Dinklage as Dr. Simon Barsinister

Jim Belushi as Dan Unger

Patrick Warburton as Cad

Alex Neuberger as Jack Unger

Taylor Momsen as Molly

John Slattery as Mayor

Amy Adams as Polly Purebred (voice)

Brad Garrett as Riff Raff (voice)

Samantha Bee as Principal

Timothy Crowe as Police Chief

Larry Vigus as Security Guard

Mario Mariani as Police Officer

Bates Wilder as Cop

Alexander 'Alex' Garde as Small Boy

Christopher Francis Byrnes as Mailman (as Christopher Byrnes)

Joe Siriani as News Stand Guy (as Joseph Siriani)

Sujoy De as Office Worker #1

Michele Proude as Office Worker #2

Albert M. Chan as Geek Worker

Jon Pierce as Hot Dog Vendor

Susie Castillo as Diana Flores

Bob Jaffe as Professor

Bruce-Robert Serafin as City Worker (as Bruce Serafin)

Lonnie Farmer as Passerby

Anthony Estrella as Male School Teacher (as Tony Estrella)

Malik McMullen as Bomb Squad Officer

Aaron Dorsey as Little Boy

Walter Covell as Old Man

Kate Lohman as Housewife

Lewis D. Wheeler as Geek with Glasses

Ellen Withrow as Female Teacher

John M. Deluca as Newscaster

Frank Ridley as Police Sergeant

Grady Justice as College Guy

Courtney O'Reagan as College Girl

Rebekah Aramini as Fox Collar Lady

Richney Fischer as Baseball Dad

Joe Stapleton as Cat Burglar Police #1

Armen Garo as Cat Burglar Police #2

Daniel Kirby as News Director

Stephen James Kidd as Bomb Squad Member (as Steve Kidd)

Rena Maliszewski as Mother

Diana Shneider as Police Secretary

Barry Blair as SWAT Captain

Bob Boehm as Bomb Squad Officer #2 (as Robert Boehm)

Lincoln P. Sisson as Bomb Squad Officer #3

Gabriel Field as Lyle

Harry L. Thomas as Police Artist

Amy Tanner as Kissing Girl

Nicole Kopka as Jogger in Park

Adam McCarthy as Capitol City Security

Roy Souza as Capitol City Cop

Tom Paolino as Capitol City Cop

Scott Dittman as Hot Dog Contestant

Ezra Buzzington as Referee

Chris Andrew Ciulla as Fireman (as Chris Ciulla)

Jay Leno as Jay Leno

Phil Morris as Supershep 1 (voice)

Michael Massee as Supershep 2 (voice)

Cam Clarke as Little Brown Dog / Supershep 3 (voice)

John DiMaggio as Bulldog / Supershep 4 (voice)

Danny Mastrogiorgio as Crazy Dog (voice)

Jess Harnell as Astronaut (voice)

Joe Bucaro III as Goon #1

Stuart F. Wilson as Goon #2

John Franchi as Observer (uncredited)

Susan Garfield as Office Worker (uncredited)

Michael Tyler Henry as Jack Unger (voice)