Boris Karloff acted in horror films.
William Henry Pratt ( 23 November 1887 -- 2 February 1969 ) , better known by his stage name Boris Karloff , was an English actor who was primarily known for his typecast roles in horror films that depicted the characters Frankenstein and The Mummy . He portrayed Frankenstein 's monster in Frankenstein ( 1931 ) , Bride of Frankenstein ( 1935 ) , and Son of Frankenstein ( 1939 ) , which resulted in his immense popularity . Bride of Frankenstein ( advertised as The Bride of Frankenstein ) is a 1935 American science fiction horror film , the first sequel to Universal Pictures ' 1931 hit Frankenstein . The Mummy is a 1932 American pre-Code horror film directed by Karl Freund .