On screen
Cast
11 credited performers
Roy Barcroft
The Purple Monster
James Craven
Dr. Cygnus Layton
Dennis Moore
Craig Foster
Linda Stirling
Sheila Layton
Bud Geary
Hodge Garrett
Artwork unavailable
Joe Whitehead
Stewart
Artwork unavailable
Fred Howard
Prof. Crandal
Artwork unavailable
Rosemonde James
Helen
Artwork unavailable
Mary Moore
Marcia
John Davidson
Emperor of Mars
Wheaton Chambers
Prof. Benjamin