Stuart Whitman

Adm. Michael Matthews

Robert Wagner

Brett

Rosemary Forsyth

Lia Holmes

Robert Colbert

Cmdr. Woody Patterson

Burr DeBenning

Aguila

Susana Miranda

Elena

Paul Stewart

Barton

Whit Bissell

Prof. Holmes

Richard Basehart

The President

Joseph Cotten

Dr. Ziegler

James Darren

Dr. Talty

Sugar Ray Robinson

Capt. Hunter

Charles Dierkop

Quinn

Larry Pennell

Bill Holmes

William Bryant

Capt. Lunderson

Robert Dowdell

Young Officer

Edward G. Robinson Jr.

Dr. Burkson

Sheila Allen

Blonde Woman

Tom Drake

Gen. Putnam

Johnny Lee

Tony

Glenna Sergent

Sally

Ray Didsbury

Security Guard

Erik L. Nelson

Triton Controller

Paul Bradley

Scientist (uncredited)

Brent Dunsford

Technician (uncredited)

George Holmes

Scientist (uncredited)

Victor Toyota

Scientist (uncredited)