cast
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Michael Rennie
Klaatu, alias Mr. Carpenter
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Patricia Neal
Helen Benson
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Billy Gray
Bobby Benson
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Sam Jaffe
Prof. Jacob Barnhardt
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Hugh Marlowe
Tom Stevens
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Lock Martin
Gort
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Freeman Lusk
General Cutler
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Edith Evanson
Mrs. Crockett, landlady
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Frank Conroy
Mr. Harley, Secretary to the President
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Frances Bavier
Mrs. Barley, boarder
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John Brown
George Barley, boarder
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Olan Soule
Mr. Krull, boarder
- Marjorie Crossland Hilda, Barnhart's secretary
- Elmer Davis Elmer Davis
- H.V. Kaltenborn H. V. Kaltenborn
- Drew Pearson Drew Pearson
- Gabriel Heatter Gabriel Heatter (voice)
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Harry Lauter
Lieutenant in Charge of Landing Site
- James Doyle Army Dr. White
- Larry Dobkin Balding Army Doctor
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Robert Osterloh
Army Examining Doctor
- Glenn Hardy Radio Interviewer at Landing Site
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Tyler McVey
Brady
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House Peters Jr.
M.P. Captain at Barnhardt's
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George Lynn
Conference Colonel Ryder
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Dorothy Neumann
Margaret, Tom's secretary
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Wheaton Chambers
Mr. Bleeker, jeweller
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Carleton Young
Zone Five Lieutenant Colonel
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Harry Harvey
The Cab Driver
- Sammy Ogg Sammy, boy witness
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Bess Flowers
Lady Outside Jewelry Store
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James Seay
Government Man (uncredited)
- Grady Galloway Radar Operator
- Hassan Khayyam Indian Newscaster
- John Barton British Newscaster
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Stuart Whitman
Sentry (scene deleted)
- Rama Bai Scientific Delegate
- John Burton British Radio Announcer
- Bill Welsh Radio Announcer (voice)
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Guy Williams
Radio Operator (uncredited)