Stephen Boyd

Character: Grant

Raquel Welch

Character: Cora

Edmond O'Brien

Character: General Carter

Donald Pleasence

Character: Dr. Michaels

Arthur O'Connell

Character: Col. Donald Reid

William Redfield

Character: Capt. Bill Owens

Arthur Kennedy

Character: Dr. Duval

Jean Del Val

Character: Jan Benes

Barry Coe

Character: Communications Aide

Ken Scott

Character: Secret Service

Shelby Grant

Character: Nurse

James Brolin

Character: Technician

Brendan Fitzgerald

Character: Wireless Operator

Brendon Boone

Character: Military Policeman (uncredited)

James Doohan

Character: Dr. Sawyer (Hypothermia technician) (uncredited)

Kenneth MacDonald

Character: Henry - Heart Monitoring (uncredited)

Christopher Riordan

Character: Young Scientist (uncredited)