Vin Diesel as The Iron Giant (voice)

Eli Marienthal as Hogarth Hughes (voice)

Jennifer Aniston as Annie Hughes (voice)

Harry Connick Jr. as Dean McCoppin (voice)

James Gammon as Foreman Marv Loach / Floyd Turbeaux (voice)

Cloris Leachman as Mrs. Lynley Tensedge (voice)

Christopher McDonald as Kent Mansley (voice)

John Mahoney as General Rogard (voice)

M. Emmet Walsh as Earl Stutz (voice)

Jack Angel as Additional Voices (voice)

Bob Bergen as Additional Voices (voice)

Mary Kay Bergman as Additional Voices (voice)

Michael Bird as Additional Voices (voice)

Devon Cole Borisoff as Additional Voices (voice)

Rodger Bumpass as Additional Voices (voice)

Robert Clotworthy as Additional Voices (voice)

Jennifer Darling as Additional Voices (voice)

Zack Eginton as Additional Voices (voice)

Paul Eiding as Additional Voices (voice)

Bill Farmer as Additional Voices (voice)

Charles Howerton as Additional Voices (voice)

Ollie Johnston as Additional Voices (voice)

Sherry Lynn as Additional Voices (voice)

Mickie McGowan as Additional Voices (voice)

Ryan O'Donohue as Additional Voices (voice)

Phil Proctor as Additional Voices (voice)

Frank Thomas as Additional Voices (voice)

Patti Tippo as Additional Voices (voice)

Brian Tochi as Additional Voices (voice)

Carole Jeghers as Firefighter Woman (voice) (uncredited)