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)