The Thirteenth Hour is a 1927 American silent film mystery produced and distributed by Metro Goldwyn Mayer and directed by Chester Franklin. The film stars Lionel Barrymore in a role where, as noted criminologist Professor Leroy, he dons a weird series of disguises to hide a dark secret. This was the first film where Barrymore was cast opposite talented dogs, and the first where he was cast as a serial killer.