Edward E. Malone
Hayden Eaton
Don Manning
Lionel Tressilian
Charlie Jordan
Nikolai Roget
Bobby Bailey
Lieut. Dan Burke
Fred Garlan
Doctor Marshall
Derek
Henry Townsend
Jules Patricia
Frank Gordon
Owen Rogers
Curtis Powell
Daniel Treve
John Trevor
Bill Ramsey
Dr. Marshall, 'The Scorpion'
Roland
Capt. Jerry Brown / Jim Lofton
Johnny Stark
Jack
Daubeney Carshott
Bill
Prince Nicholas Petroff
George Edward Blaine
Donald Marshall
Robert Thornton
Philip Lennox
Agent Ted Kelly
David Beresford
Frederick Graves
Waite Lifter
Ned Thayer
Philip Collett
Jimmy Milligan
John Trott
Capt. John Kent
Graham Smith
Attorney Johnson
John Ainsworth
Luther Flint
Ted 'Rip-Roaring' Riley
Andrew Robinson
Dr. Steven Russell
Bart Wallace
Eddie Carter
John King
Reporter (uncredited)
Sam Gladding
Bruce Donaldson
Jack Hare
Jerry Booth
Gil Barry
Cal
Franz Pless
Marshall Jones
Felipe
Theodore Wayne
Dick Revel
Oliver Wendell Blaine
Dr. Craig Mitchell
Cody Jacques
Dick Forrest
Himself
Julian Perryam
Richard Castleman / Danny Rowland
Jerry
Tad Worden
The Hero
Dr. Robert Sanford
Blair Farquar
John Barton
Rance Conway
Roger Moran
Dr. Bradford