Marvin
Dr. Cygnus Layton
Dr. Bryant
Drake
Commodore Carlson
M. De Treville
Captain Hornsby
Daniels (uncredited)
Prof. Millard
Henry Mills
Dr. Bryant
Swenson (uncredited)
Stage Actor Playing Philip Mannings
Commishioner Litchfield
Prof. Millard
John Wheeler
Prof. James Clayton [Chs. 1, 10-12]
Dr. George Strong
Mordigan
Cal Sutton
Interpreter (uncredited)
Cavalier (uncredited)
Bismo - Annabella's Friend (uncredited)
Mr. Winters
Bidwell
Ace Diamond
Dr. Cyrus Layton
Major Morris
Commissioner Robert George Hardy [Chs. 5-7]
Officer (uncredited)
Thomas (uncredited)
Lloyd Chapin
Fire Warden
Ivan Shark
Joseph Rand
Giovanni (Uncredited)
Instructor
Captain in Car (uncredited)
Dan Slocum
'Dandy' Darnell
Abel Bellamy
