Klaatu, alias Mr. Carpenter

Helen Benson

Bobby Benson

Prof. Jacob Barnhardt

Tom Stevens

Gort

General Cutler

Mrs. Crockett, landlady

Mr. Harley, Secretary to the President

Mrs. Barley, boarder

George Barley, boarder

Mr. Krull, boarder

Hilda, Barnhart's secretary

Elmer Davis

H. V. Kaltenborn

Drew Pearson

Gabriel Heatter (voice)

Lieutenant in Charge of Landing Site

Army Dr. White

Balding Army Doctor

Army Examining Doctor

Radio Interviewer at Landing Site

Brady

M.P. Captain at Barnhardt's

Conference Colonel Ryder

Margaret, Tom's secretary

Mr. Bleeker, jeweller

Zone Five Lieutenant Colonel

The Cab Driver

Sammy, boy witness

Lady Outside Jewelry Store

Government Man

Radar Operator

Indian Newscaster

British Newscaster

Sentry (scene deleted)

Scientific Delegate

British Radio Announcer

Radio Announcer (voice)