Michael Rennie

Klaatu, alias Mr. Carpenter

Patricia Neal

Helen Benson

Billy Gray

Bobby Benson

Sam Jaffe

Prof. Jacob Barnhardt

Hugh Marlowe

Tom Stevens

Lock Martin

Gort

Freeman Lusk

General Cutler

Edith Evanson

Mrs. Crockett, landlady

Frank Conroy

Mr. Harley, Secretary to the President

Frances Bavier

Mrs. Barley, boarder