Eduardo Ciannelli as Doctor Satan

Robert Wilcox as Bob Wayne / Copperhead

William Newell as Speed Martin

C. Montague Shaw as Prof. Thomas Scott

Ella Neal as Lois Scott

Dorothy Herbert as Alice Brent

Charles Trowbridge as Gov. Bronson

Jack Mulhall as Police Chief Rand

Edwin Stanley as Col. Bevans

Walter McGrail as Stoner

Joe McGuinn as Gort

Bud Geary as Hallett

Paul Marion as Corbay

Archie Twitchell as Ross

Lynton Brent as Scarlett

Ken Terrell as Corwin

Al Taylor as Joe

George Allen as Henchman-Driver Spike

John Bagni as Gray, Pick-up Thug

Frank Brownlee as Panamint Pete

James Bush as Co-Pilot

Yakima Canutt as Sailor at Winch

Virginia Carroll as Nurse

Ed Cassidy as Barton

Davison Clark as Police Lieutenant

Tris Coffin as Wells - Governor's Secretary

Frank Conklin as Station Master Burns

Fred Criswell as Officer

Eddie Dew as Gas Station Attendant

Frank Ellis as Plant Henchman

James Fawcett as Al

Sam Garrett as Roper

Duke Green as Duke - Mine Thug

Alan Gregg as Red - Mine Thug

Kenneth Harlan as Capt. Lathrop

Charles Hutchison as Proprietor

Jerry Jerome as House Heavy

Patrick Kelly as Plant Henchman

Marten Lamont as Steve - Pilot

Bert LeBaron as Henchman Fallon

Jack O'Shea as House Heavy

Eddie Parker as Chuck - Lead Truck Thug

Hal Price as P&G Warehouse Mgr.

Ernest Sarracino as Henchman-Guard

Cy Schindell as Jake - Biplane Pilot

William Stahl as Detective Brock

Ted Stanhope as Warehouse Watchman

Tom Steele as Truck Henchman

Harry Strang as Police Officer Davis

Duke Taylor as Watkins - Fire Escape Thug

Robert Wayne as Detective Perry

Wally West as Palmer - Thug

Lloyd Whitlock as Prof. Williams

Bill Wilkus as Truck Henchman

Bud Wolfe as Sailor at Cable