Frank Merriwell (as Don Briggs)
Elsie Belwood
Bruce Browning (as John King)
Carla Rogers
House Peters
'Hersh' Mayall
Wally Reid
Eddie Arnold
Bryant Washburn
Allen Hersholt
Carlyle Blackwell
Peter Gowland
Harry
Charles Merriwell [Chs.10-12] (as William Carleton)
Daggett (as Bentley Hewlett)
Mrs. Mary Merriwell [Chs. 2, 10-12]
Murray Belwood [Chs. 4-9]
Coach Harding [Chs. 1-2, 11-12]
Black - Henchman (as Alan Bridge)
Jeff [Chs. 2, 10-12]
Chemistry Professor (uncredited)
Lion Tamer (archive footage) (uncredited)
Indian John (uncredited)
Helpful Driver (uncredited)
Mrs. McLaw (uncredited)
Pete (uncredited)
Bill / Stalking Indian (uncredited)
Road Crew Foreman (uncredited)
Dr. Cummings (uncredited)
Captain of the 'Viking' (uncredited)
Big Tom (uncredited)
Barbecue Cook (uncredited)
Baseball Game Announcer (uncredited)
Lumber Camp Cook (uncredited)
Dance Party Guest (uncredited)
Slout (uncredited)
Theater Doorman (uncredited)
Football Player (uncredited)
Jimmy McLaw (uncredited)
Man in Audience (archive footage) (uncredited)
Dave (uncredited)
Mrs. Belwood (uncredited)
Yacht Captain (uncredited)
Man in Front Row (archive footage) (uncredited)
Second Mate of the 'Viking' [Chs. 4-5] (uncredited)
Berger (uncredited)
Monte (uncredited)
Rurale Captain (uncredited)
Yacht Crewman (uncredited)
George Baldwin (uncredited)
Indian (uncredited)
Gorman (uncredited)
Trapeze Artist (archive footage) (uncredited)
Chief Tonaka (uncredited)
Prof. Baldwin (uncredited)
Pug O'Leary (uncredited)
Lang (uncredited)
Joe (uncredited)
Nolan (uncredited)
Judd (uncredited)