Son of Frankenstein is a 1939 American horror film directed by Rowland V. Lee and starring Basil Rathbone, Boris Karloff and Bela Lugosi. The film is the third in Universal Pictures' Frankenstein series and is the follow-up to the 1935 film Bride of Frankenstein. Son of Frankenstein stars Rathbone as Baron Wolf von Frankenstein who, with his wife Elsa (Josephine Hutchinson) and son Peter (Donnie Dunagan), returns to his late father's estate. Near the castle lives Ygor (Bela Lugosi), a crazed blacksmith whose neck was broken in an unsuccessful hanging attempt. Among the castle's remains, Frankenstein discovers the remains of the Monster (Boris Karloff) and decides to try to save his family name by resurrecting the creature to prove his father was correct. He finds, however, the Monster only responds to Ygor's commands.

The film was originally announced in August 1938 after a successful theatrical reissue of Dracula and Frankenstein. Son of Frankenstein was initially announced under the title After Frankenstein. The screenplay written by Willis Cooper was initially rejected and early script drafts included only the characters that would be used in the final film. The original budget was set at $250,000 but Lee increased it to $300,000 and had a 27-day shooting schedule. Difficulties in production arose when Lee was unsatisfied with the script. Production was delayed until November 9 due to inclement weather and other problems, and filming was completed on January 5, 1939, with a final cost of $420,000. The film was released on January 13, 1939, and received positive reviews from The New York Daily News, The New York Times, Variety and the Monthly Film Bulletin. A sequel, The Ghost of Frankenstein, was released in 1942.