John Baragrey as Dr. Henry Spensser

Mala Powers as Anne Spensser

Otto Kruger as Dr. William Spensser

Robert Hutton as Dr. John Robert Carrington

Ross Martin as Dr. Jeremy 'Jerry' Spensser

Ed Wolff as The Colossus

Charles Herbert as Billy Spensser

Dick Nelson as Charles - Chauffeur-Butler

Roy Engel as Police Inspector

Charles Sherlock as Airline Pilot