- Rex
- Rex, The King of Wild Horses
- Rin Tin Tin Jr.
- Rinty
- Kane Richmond
- Frank Bradley
- Norma Taylor
- Dorothy Bruce
- Mischa Auer
- Tanaga [Chs. 1, 4, 8, 10-12]
- Smiley Burnette
- Jensen
- Harry Woods
- Crawford
- Pedro Regas
- Pasha [Chs. 1-4, 7-11]
- Hooper Atchley
- Debor [Chs. 11-12]
- Wheeler Oakman
- Henchman Wheeler
- Victor Potel
- Kinso, Royal Guard Commander [Chs. 1, 10-12]
- Allan Cavan
- Mr. Bruce [Chs. 1-3, 9]
- Al Bridge
- Henchman Mitchell [Chs. 1-6, 10]
- Edmund Cobb
- Henchman Jones
- Charles King
- Henchman Martin
- George Chesebro
- Henchman Anderson
- Jack Rockwell
- Henchman McDonald [Chs. 2,3,5-7,9]
- Ralph Byrd
- Forest Ranger Jerry Morton [Chs. 5-6]
- Jack Cheatham
- First Policeman [Ch. 1]
- Tracy Layne
- Henchman Buck Foster [Chs. 9-10]
- Wilfred Lucas
- Frank Hammond [Ch. 5]
- Frankie Marvin
- Guard [Chs. 11-12]
- Eddie Parker
- Guard
- Max Wagner
- Tramp [Ch. 5]
