• 
  Rick Baker

  Gorilla
• 
  Ray Milland

  Maxwell Kirshner
• 
  John Dullaghan

  Thomas
• 
  John G. Jones

  Maxwell Kirshner
• 
  Tommy Cook

  Medical Salesman
• 
  Kathrine Baumann

  Patricia
• 
  Wes Bishop

  Dr. Smith
• 
  John Bliss

  Donald

• 
  Chelsea Brown

  Lila
• 
  John Dullaghan

  Thomas
• 
  Lee Frost

  Sergeant Hacker
• 
  Bruce Kimball

  Police Lieutenant
• 
  Roger Gentry

  Police Sergeant
• 
  Roosevelt Grier

  Jack Moss (as 'Rosey' Grier)
• 
  Jane Kellem

  Miss Mullen

• 
  Don Marshall

  Dr. Fred Williams
• 
  Britt Nilsson

  Nurse
• 
  Roger Perry

  Dr. Philip Desmond

• 
  Charles Minsky

  camera and electrical departme
• 
  Robert O. Ragland

  departament sunet
• 
  Samuel Z. Arkoff

  miscellaneous crew
• 
  Rick Baker

  special effects
• 
  Daniel C. Striepeke

  special effects
• 
  Tom Barman

  special effects