 Basil RathboneSherlock Holmes | Sherlock Holmes |
 Nigel BruceDr. John Watson | Dr. John Watson |
 Hillary BrookeLydia Marlowe | Lydia Marlowe |
 Henry DaniellProfessor James Moriarty | Professor James Moriarty |
 Paul CavanaghSir George Fenwick | Sir George Fenwick |
 Matthew BoultonInspector Gregson | Inspector Gregson |
 Eve AmberMaude Fenwick | Maude Fenwick |
 Frederick WorlockDr. Onslow | Dr. Onslow |
| PPercival VivianDr. Simnell | Dr. Simnell |
 Coulter IrwinCorporal Williams | Corporal Williams |
 Sally ShepherdCrandon | Crandon |
 Mary GordonMrs. Hudson | Mrs. Hudson |
| JJohn BurtonWaring the Mesmerist (uncredited) | Waring the Mesmerist (uncredited) |
| HHarold De BeckerShoelace Vendor Henchman (uncredited) | Shoelace Vendor Henchman (uncredited) |
| TTony EllisCarter the Hypnotized Subject (uncredited) | Carter the Hypnotized Subject (uncredited) |
 Bess FlowersBar Patron (seen in mirror) (uncredited) | Bar Patron (seen in mirror) (uncredited) |
 Kay Harding4th Victim (uncredited) | 4th Victim (uncredited) |
| AAlec HarfordCommissioner of the CID (uncredited) | Commissioner of the CID (uncredited) |
 Olaf HyttenFenwick's Butler Norris (uncredited) | Fenwick's Butler Norris (uncredited) |
 Boyd IrwinShort-Tempered Officer Closing Window (uncredited) | Short-Tempered Officer Closing Window (uncredited) |
 Eric MayneMember of Mesmer Club (uncredited) | Member of Mesmer Club (uncredited) |
 William H. O'BrienPembrook House Waiter (uncredited) | Pembrook House Waiter (uncredited) |
