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

Harvey Livermore
Tony Hill

Phil Douglas

Ned Tyler

Robert Ardis