The Master Key

Milburn Stone

Agent Tom Brant

Jan Wiley

Janet Lowe

Dennis Moore

Jack Ryan

Addison Richards

Gerhard Doenitz / Garret Donahue

Byron Foulger

Prof. Elwood Henderson

Maris Wrixon

Dorothy Newton

Sarah Padden

Aggie

George Lynn

Herman

Russell Hicks

Police Chief Michael J. O'Brien

Roland Varno

Arnold Hoffman

Lash LaRue

Migsy

Jerry Shane

Dan

Neyle Morrow

Spike

John Eldredge

Walter Stark

The Phantom Rider

The Wolf Dog

Perils of the Royal Mounted

Beatrice Fairfax

Dr. Mabuse, the Gambler

The Lightning Raider

The Lost Express

Lucille Love: The Girl of Mystery

The House of Hate

King of the Circus

Perils of Nyoka

Go Get 'Em Hutch

The Adventures of Smilin' Jack

The Girl and the Game

The Hazards of Helen

King of the Forest Rangers

The Black Coin

Custer's Last Stand

King of the Texas Rangers

Jungle Menace