Films[]
- 1931 – The Mad Genius as Fedor's abusive father
- 1931 – Frankenstein as Frankenstein's Monster
- 1932 – Behind the Mask as Jim Henderson
- 1932 – The Old Dark House as Morgan
- 1932 – The Mummy as Imhotep and Ardath Bey
- 1933 – The Ghoul as Professor Morlant
- 1934 – The Black Cat as Hjalmar Poelzig
- 1935 – Bride of Frankenstein as Frankenstein's Monster
- 1935 – The Raven as Edmond Bateman
- 1935 – The Black Room as Gregor de Berghmann and Anton de Berghmann
- 1936 – The Invisible Ray as Dr. Janos Rukh
- 1936 – The Walking Dead as John Ellman
- 1936 – The Man Who Changed His Mind as Dr. Laurience
- 1939 – Son of Frankenstein as Frankenstein's Monster
- 1939 – The Man They Could Not Hang as Dr. Henryk Savaard
- 1939 – Tower of London as Mord
- 1940 – Black Friday as Dr. Ernest Sovac
- 1940 – The Man with Nine Lives as Dr. Leon Kravaal
- 1940 – Before I Hang as Dr. John Garth
- 1940 – The Ape as Dr. Bernard Adrian
- 1941 – The Devil Commands as Dr. Julian Blair
- 1942 – The Boogie Man Will Get You as Professor Nathaniel Billings
- 1944 – The Climax as Dr. Friedrich Hohner
- 1944 – House of Frankenstein as Dr. Gustav Niemann
- 1945 – The Body Snatcher as John Gray
- 1945 – Isle of the Dead as General Nikolas Pherides
- 1946 – Bedlam as Master George Sims
- 1949 – Abbott and Costello Meet the Killer, Boris Karloff as Swami Talpur
- 1951 – The Strange Door as Voltan
- 1952 – The Black Castle as Dr. Meissen
- 1953 – Abbott and Costello Meet Dr. Jekyll and Mr. Hyde as Dr. Henry Frankenstein and Mr. Hyde
- 1954 – The Monster of the Island as Don Gaetano
- 1957 – Voodoo Island as Dr. Phillip Knight
- 1958 – The Haunted Strangler as James Rankin
- 1958 – Frankenstein 1970 as Baron Victor von Frankenstein
- 1958 – Corridors of Blood as Dr. Thomas Bolton
- 1962 – Arsenic & Old Lace as Jonathan Brewster
- 1963 – The Raven as Dr. Scarabus
- 1963 – The Terror as Baron Victor von Leppe
- 1963 – Black Sabbath as Gorca
- 1963 – The Comedy of Terrors as Amos Hinchley
- 1965 – Die, Monster, Die! as Nathum Whitley
- 1966 – The Ghost in the Invisible Bikini as Hiram Stokely
- 1967 – Mad Monster Party as Baron Boris von Frankenstein (voice)
- 1967 – The Sorcerers as Professor Marcus Montserrat
- 1967 – Cauldron of Blood as Charles Franz Baduescu
- 1970 – Curse of the Crimson Altar as Professor Marsh
- 1970 – Isle of the Snake People as Karl van Molder and Damballah
- 1971 – The Incredible Invasion as Professor John Mayer
- 1971 – Fear Chamber as Dr. Carl Mandel
- 1972 – House of Evil as Mathias Morteval