Sherlock Holmes
Dr. John Watson
Lydia Marlowe
Professor James Moriarty
Sir George Fenwick
Inspector Gregson
Maude Fenwick
Dr. Onslow
Dr. Simnell
Corporal Williams
Crandon
Mrs. Hudson
Waring the Mesmerist (uncredited)
Shoelace Vendor Henchman (uncredited)
Carter the Hypnotized Subject (uncredited)
Bar Patron (seen in mirror) (uncredited)
4th Victim (uncredited)
Commissioner of the CID (uncredited)
Fenwick's Butler Norris (uncredited)
Short-Tempered Officer Closing Window (uncredited)
Member of Mesmer Club (uncredited)
Pembrook House Waiter (uncredited)