Rex Reason as Dr. Cal Meacham

Faith Domergue as Dr. Ruth Adams

Jeff Morrow as Exeter

Lance Fuller as Brack

Robert Nichols as Joe Wilson

Russell Johnson as Steve Carlson

Douglas Spencer as The Monitor of Metaluna

Richard Deacon as Spacecraft Pilot

Regis Parton as Mutant

Karl Ludwig Lindt as Dr. Adolph Engelborg

Robert B. Williams as Webb

Coleman Francis as Express Deliveryman