Lloyd Hughes

As Edward E. Malone

As Hayden Eaton

As Don Manning

As Lionel Tressilian

As Charlie Jordan

As Nikolai Roget

As Bobby Bailey

As Lieut. Dan Burke

As Fred Garlan

As Doctor Marshall

As Derek

As Henry Townsend

As Jules Patricia

As Frank Gordon

As Owen Rogers

As Curtis Powell

As Daniel Treve

As John Trevor

As Bill Ramsey

As Dr. Marshall, 'The Scorpion'

As Roland

As Capt. Jerry Brown / Jim Lofton

As Johnny Stark

As Jack

As Daubeney Carshott

As Bill

As Prince Nicholas Petroff

As George Edward Blaine

As Donald Marshall

As Robert Thornton

As Philip Lennox

As Agent Ted Kelly

As David Beresford

As Frederick Graves

As Waite Lifter

As Ned Thayer

As Philip Collett

As Jimmy Milligan

As John Trott

As Capt. John Kent

As Graham Smith

As Attorney Johnson

As John Ainsworth

As Luther Flint

As Ted 'Rip-Roaring' Riley

As Andrew Robinson

As Dr. Steven Russell

As Bart Wallace

As Eddie Carter

As John King

As Reporter (uncredited)

As Sam Gladding

As Bruce Donaldson

As Jack Hare

As Jerry Booth

As Gil Barry

As Cal

As Franz Pless

As Marshall Jones

As Felipe

As Theodore Wayne

As Dick Revel

As Oliver Wendell Blaine

As Dr. Craig Mitchell

As Cody Jacques

As Dick Forrest

As Himself

As Julian Perryam

As Richard Castleman / Danny Rowland

As Tad Worden

As Jerry

As The Hero

As Dr. Robert Sanford

As Blair Farquar

As John Barton

As Rance Conway

As Roger Moran

As Dr. Bradford

As Harvey Livermore