Gerald Mohr as Col. Thomas O`Bannion

Naura Hayden as Dr. Iris Ryan

Les Tremayne as Prof. Theodore Gettell

Jack Kruschen as CWO Sam Jacobs

Paul Hahn as Maj. Gen. George Treeger

J. Edward McKinley as Prof. Paul Weiner

Tom Daly as Dr. Frank Gordon

Don Lamond as TV Newscaster / Narrator / Martian (voice)

Edward Innes as Brig. Gen. Alan Prescott

Gordon Barnes as Maj. Lyman Ross

Jack Haddock as Lt. Col. Davis

Brandy Bryan as Nurse Hayes

Joan Fitzpatrick as Nurse Dixon

Duke Norton as Dr. Muller

William Remick as Dr. Hawley

David De Haven as Air Force News Photographer

Arline Hunter as Joan

Alean 'Bambi' Hamilton as Joan's Friend

Fred Ross as Air Force News Photographer