The Shadow was a popular American radio drama that aired from 1937 to 1954, featuring crime, mystery, and suspense. Its main character, Lamont Cranston, used hypnotic powers to cloud people's minds and fight criminals. Famous for the catchphrase “Who knows what evil lurks in the hearts of men? The Shadow knows!”, the series starred actors including Orson Welles and Bret Morrison. It became a classic of old-time radio and helped influence the superhero genre.