• 
  William Cameron Menzies

  regizor

• 
  Leif Erickson

  Mr. George MacLean
• 
  Douglas Kennedy

  Tall cop Jackson who vanishes
• 
  Bob Herron

  Martian
• 
  Charles Cane

  Old cop Blaine who vanishes
• 
  Milburn Stone

  Capt. Roth - army technician
• 
  Morris Ankrum

  Col. Fielding
• 
  Frank Wilcox

  Pentagon Chief of Staff

• 
  Peter Brocco

  Brainard, Wilson's aide
• 
  Arthur Franz

  Dr. Kelston - astronomer/Narrator
• 
  John Eldredge

  Mr. Turner
• 
  Lock Martin

  Mutant carrying David to 'Intelligence'
• 
  Bert Freed

  Police Chief A.C.Barrows
• 
  Richard Deacon

  MP
• 
  Hillary Brooke

  Mrs. Mary MacLean

• 
  Helena Carter

  Dr. Pat Blake
• 
  Jimmy Hunt

  David MacLean
• 
  Janine Perreau

  Kathy Wilson
• 
  William Phipps

  Sgt. Baker (as Bill Phipps)
• 
  Max Wagner

  Sgt. Rinaldi

• 
  Boris Leven

  art director
• 
  John F. Seitz

  imagine
• 
  Norma Koch

  costume
• 
  Arthur Roberts

  montaj
• 
  Edward L. Alperson

  producător
• 
  William Cameron Menzies

  design de producţie
• 
  Edward G. Boyle

  set decorator
• 
  Jack Cosgrove

  special effects
• 
  Howard Lydecker

  visual effects