The Mad Doctor of Market Street is a 1942 American horror film produced by Universal Pictures starring Lionel Atwill. The film was a low-budget project that utilized the studio's contract players and gave rising director Joseph H. Lewis an opportunity to demonstrate his versatility with little production money.

Lionel Alfred William Atwill was an English and American stage and screen actor. He began his acting career at the Garrick Theatre. After coming to the United States, he appeared in Broadway plays and Hollywood films. Some of his more significant roles were in Captain Blood (1935), Son of Frankenstein (1939) and To Be or Not to Be (1942).