Lloyd Bridges

Colonel Floyd Graham

Osa Massen

Dr. Lisa Van Horn

John Emery

Dr. Karl Eckstrom

Noah Beery Jr.

Major William Corrigan

Hugh O'Brian

Harry Chamberlain

Morris Ankrum

Dr. Ralph Fleming

Patrick Aherne

Reporter #1

Sherry Moreland

Martian girl

John Dutra

Physician

Kathy Marlowe

Reporter

Tom Coleman

Reporter (uncredited)

James Conaty

Doctor Taking Lisa's Blood Pressure (uncredited)

Sam Harris

Reporter at Press Briefing (uncredited)

Judd Holdren

Reporter #3 (uncredited)

Stuart Holmes

Reporter (uncredited)

Kurt Neumann