Sherlock Holmes
Basil Rathbone
Dr. John Watson
Nigel Bruce
Crandon
Sally Shepherd
Mrs. Hudson
Mary Gordon
Waring the Mesmerist (uncredited)
John Burton
Shoelace Vendor Henchman (uncredited)
Harold De Becker
Carter the Hypnotized Subject (uncredited)
Tony Ellis
Bar Patron (seen in mirror) (uncredited)
Bess Flowers
4th Victim (uncredited)
Kay Harding
Commissioner of the CID (uncredited)
Alec Harford
Fenwick's Butler Norris (uncredited)
Olaf Hytten
Short-Tempered Officer Closing Window (uncredited)
Boyd Irwin
Lydia Marlowe
Hillary Brooke
Member of Mesmer Club (uncredited)
Eric Mayne
Pembrook House Waiter (uncredited)
William H. O'Brien
Professor James Moriarty
Henry Daniell
Sir George Fenwick
Paul Cavanagh
Inspector Gregson
Matthew Boulton
Maude Fenwick
Eve Amber
Dr. Onslow
Frederick Worlock
Dr. Simnell
Percival Vivian
Corporal Williams
Coulter Irwin
Director of Photography
Virgil Miller
Novel
Arthur Conan Doyle
Producer
Roy William Neill
Director
Editor
Edward Curtiss
Costume Design
Vera West
Set Decoration
Russell A. Gausman
Special Effects
John P. Fulton
Art Direction
John B. Goodman
Assistant Director
Melville Shyer
Screenplay
Bertram Millhauser
Ted von Hemert
Sound Director
Bernard B. Brown
Music Director
Mark Levant
Martin Obzina
Camera Operator
Roswell A. Hoffmann