Stephen Boyd as Grant

Raquel Welch as Cora

Edmond O'Brien as General Carter

Donald Pleasence as Dr. Michaels

Arthur O'Connell as Col. Donald Reid

William Redfield as Capt. Bill Owens

Arthur Kennedy as Dr. Duval

Jean Del Val as Jan Benes

Barry Coe as Communications Aide

Ken Scott as Secret Service

Shelby Grant as Nurse

James Brolin as Technician

Brendan Fitzgerald as Wireless Operator

Brendon Boone as Military Policeman (uncredited)

James Doohan as Dr. Sawyer (Hypothermia technician) (uncredited)

Kenneth MacDonald as Henry - Heart Monitoring (uncredited)

Christopher Riordan as Young Scientist (uncredited)