Richard Eyer

Timmie Merrinoe

Philip Abbott

Dr. Tom Merrinoe

Diane Brewster

Mary Merrinoe

Harold J. Stone

Gen. Swayne

Robert H. Harris

Prof. Frank Allerton

Dennis McCarthy

Col. Macklin

Alexander Lockwood

Arthur Kelvaney

John O'Malley

Prof. Baine

Gage Clarke

Dr. Bannerman

Than Wyenn

Prof. Zeller

Jefferson Dudley Searles

Prof. Foster

Alfred Linder

Martin / Computer

Ralph Votrian

1st Gate Sergeant

Michael Miller

2nd Gate Sergeant

Rayford Barnes

Capt. McLaren (uncredited)

Helen Kleeb

Miss Vandergrift (uncredited)

Alvy Moore

Scientist (uncredited)

Gary Vinson

Young soldier (uncredited)

Marvin Miller

Robby the Robot (voice) (uncredited)