While the City Sleeps is a 1956 American film noir directed by Fritz Lang and starring Dana Andrews, Rhonda Fleming, George Sanders, Howard Duff, Thomas Mitchell, Vincent Price, John Drew Barrymore and Ida Lupino. Written by Casey Robinson, the newspaper drama was based on The Bloody Spur by Charles Einstein, which was inspired by the case of Chicago serial killer William Heirens. Five decades after the film's release, critic Dennis Schwartz wrote, "Fritz Lang ('M') directs his most under-appreciated great film, more a social commentary than a straight crime drama."

Friedrich Christian Anton Lang, better known as Fritz Lang, was an Austrian-American film director, screenwriter, and producer who worked in Germany and later the United States. One of the best-known émigrés from Germany's school of Expressionism, he was dubbed the "Master of Darkness" by the British Film Institute. He has been cited as one of the most influential filmmakers of all time.