Ewan McGregor
Rodney Copperbottom (voice)

Halle Berry
Cappy (voice)

Greg Kinnear
Ratchet (voice)

Mel Brooks
Bigweld (voice)

Drew Carey
Crank (voice)

Amanda Bynes
Piper (voice)

Robin Williams
Fender (voice)

Jim Broadbent
Madame Gasket (voice)

Stanley Tucci
Herb Copperbottom (voice)

Dianne Wiest
Mrs. Copperbottom (voice)

Harland Williams
Lug (voice)

Jennifer Coolidge
Aunt Fanny (voice)

Paul Giamatti
Tim the Gate Guard (voice)

Natasha Lyonne
Loretta Geargrinder (voice)

Chris Wedge
Wonderbot / Phone Booth (voice)

Dan Hedaya
Mr. Gunk (voice)

Marshall Efron
Lamppost / Toilet Bot / Bass Drum / Microphone

Terry Bradshaw
Broken Arm Bot (voice)

Al Roker
Mailbox (voice)

Lucille Bliss
Pigeon Lady (voice)

Jay Leno
Fire Hydrant (voice)

Lowell Ganz
Mr. Gasket (voice)

Paula Abdul
Watch (voice)

Jackie Hoffman
Water Cooler (voice)

Brian Scott McFadden
Trashcan Bot (voice)

James Earl Jones
Voice Box at Hardware Store (voice)

Damien Fahey
Stage Announcer (voice)

Stephen Tobolowsky
Bigmouth Executive / Forge (voice)

Jansen Panettiere
Younger Rodney (voice)

Will Denton
Young Rodney (voice)

Crawford Wilson
Young Rodney (voice)

Alan Rosenberg
Jack Hammer (voice)

Lara Cody
Additional Voices

David Crommett
Additional Voices

Darin De Paul
Additional Voices

Dann Fink
Additional Voices

Ray Iannicelli
Additional Voices

Sondra James
Additional Voices

Vanessa Lemonides
Additional Voices

Bruce Winant
Additional Voices / ADR Loop Group

Chris Moyles
Stage Announcer (voice)

Chingy
DJ Robot (uncredited)

Randy Jackson
Watch #2 (voice) (uncredited)

James Brown
Diesel (archive footage) (uncredited)