Rex Reason

Dr. Cal Meacham

Faith Domergue

Dr. Ruth Adams

Jeff Morrow

Exeter

Lance Fuller

Brack

Robert Nichols

Joe Wilson

Russell Johnson

Steve Carlson

Douglas Spencer

The Monitor of Metaluna

Karl Ludwig Lindt

Dr. Adolph Engelborg

Regis Parton

Mutant (uncredited)

Richard Deacon

Pilot (uncredited)

Coleman Francis

Express Deliveryman (uncredited)

Robert B. Williams

Webb (uncredited)

Charlotte Alpert

Metaluna Woman at Decompression Console (uncredited)

Spencer Chan

Dr. Hu Ling Tang (uncredited)

Lizalotta Valesca

Dr. Marie Pitchner (uncredited)