• 
  Jack Kruschen

  CWO Sam Jacobs
• 
  Gerald Mohr

  Col. Thomas O'Bannion
• 
  Ralph Brooks

  Security Man at Briefing
• 
  Les Tremayne

  Prof. Theodore Gettell
• 
  Ted Cassidy

  Martian
• 
  Gordon Barnes

  Maj. Lyman Ross
• 
  Brandy Bryan

  Nurse Hayes
• 
  Jack Haddock

  Lt. Col. Davis

• 
  Paul Hahn

  Maj. Gen. George Treegar
• 
  Naura Hayden

  Dr. Iris 'Irish' Ryan
• 
  Edward Innes

  Brig. Gen. Alan Prescott
• 
  Don Lamond

  TV Newscaster / Narrator / Martian (voice)
• 
  J. Edward McKinley

  Prof. Paul Weiner
• 
  Duke Norton

  Dr. Muller
• 
  Joan Patrick

  Nurse Dixon (as Joan Fitzpatrick)

• 
  William Remick

  Dr. Hawley (as Wm. Remick)
• 
  Tom Daly

  Dr. Frank Gordon

• 
  Stanley Cortez

  imagine
• 
  Marjorie Corso

  costume and wardrobe departmen
• 
  David Newell

  make-up department