Mr. District Attorney is a radio crime drama, produced by Samuel Bischoff, which aired on NBC and ABC from April 3, 1939 to June 13, 1952. The show focuses on a crusading district attorney, initially known as Mister District Attorney or Chief, who later becomes known as Paul Garrett. The series was created, written, and directed by former law student Ed Byron, and was inspired by the early years of New York governor Thomas E. Dewey.

The show began as a 15-minute serial, which later transitioned into a half-hour, self-contained series. Produced in New York City, the program is notable for its attention to detail and accuracy, with its creator Ed Byron researching crime statistics and embedding himself in rough bars to gather insights from both criminals and the police. The show was successful, regularly competing with Jack Benny and Bob Hope in the ratings, and even attracting the attention of the FBI due to its accurate crime predictions.

The lead role of Mr. District Attorney was played by several actors during its run, including Dwight Weist, Raymond Edward Johnson, Jay Jostyn, and David Brian. Other main characters include Edith Miller, the district attorney's secretary, and Len Harrington, the D.A.'s chief investigator. The series was later translated to television with the same characters and cast reprising their roles.