Michael Rennie
Klaatu / 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
Frank Conroy
Mr. Harley
Frances Bavier
Mrs. Barley
John Brown
George Barley
Olan Soule
Mr. Krull
Marjorie Crossland
Hilda
Elmer Davis
Elmer Davis
H.V. Kaltenborn
H. V. Kaltenborn
Drew Pearson
Drew Pearson
Gabriel Heatter
Gabriel Heatter (voice)
Harry Lauter
Lieutenant in Charge of Landing Site
James Doyle
Army Dr. White
Larry Dobkin
Balding Army Doctor
Robert Osterloh
Army Examining Doctor
Glenn Hardy
Radio Interviewer at Landing Site
Tyler McVey
Brady
House Peters Jr.
M.P. Captain at Barnhardt's
George Lynn
Conference Colonel Ryder
Dorothy Neumann
Margaret
Wheaton Chambers
Mr. Bleeker
Carleton Young
Zone Five Lieutenant Colonel
Harry Harvey
The Cab Driver
Sammy Ogg
Sammy
Bess Flowers
Lady Outside Jewelry Store
James Seay
Government Man (uncredited)
Grady Galloway
Radar Operator
Hassan Khayyam
Indian Newscaster
John Barton
British Newscaster
Stuart Whitman
Sentry (deleted scene)
Rama Bai
Scientific Delegate
John Burton
British Radio Announcer
Bill Welsh
Radio Announcer (voice)
Guy Williams
Radio Operator (uncredited)