First in films as a stunt double for
Mary Pickford. Given star billing at Vitagraph for a series of comedies alongside
Earl Montgomery in 1917. Left after four years to set up his own production company which turned out 'Standard' or 'Blue Ribbon' comedies. His brother
Murray Rock acted as production manager, and
Norman Taurog became chief director. By the mid-'20s Rock had several famous comedians under contract:
Jimmy Aubrey,
Stan Laurel,
Chester Conklin,
Gale Henry,
Billy Franey and others. He released his product first through
Lewis J. Selznick and (after Selznick went bankrupt) through Film Booking Office (FBO). Rock also had a British subsidiary at Elstree, which continued on into the '40s.