Nicolas Cage
Dr. Tenma (voice)

Madeline Carroll
Widget (voice)

Freddie Highmore
Astro Boy (voice)

Kristen Bell
Cora (voice)

Donald Sutherland
General Stone (voice)

Bill Nighy
Dr. Elefun (voice)

Eugene Levy
Orrin (voice)

Sterling Beaumon
Sludge (voice)

Nathan Lane
Ham Egg (voice)

Samuel L. Jackson
Zog (voice)

Charlize Theron
Narrator

David Alan Grier
Mr. Squirt / Math Cowboy / Boxer Robot

Alan Tudyk
Mr. Squeegee / Scrapheap Head / Stinger Two

Newell Alexander
General Heckler (voice)

Elle Fanning
Grace (voice)

Dee Bradley Baker
Trashcan (voice)

Moisés Arias
Zane (voice)

Ryan Stiles
Mr. Moustachio/Burning Robot (voice)

Matt Lucas
Sparx (voice)

Sofia Bowers
The Little Stinker (voice)