Diamond Lil is a 1928 play by American actress and playwright Mae West. Prior to Diamond Lil, she had written a number of plays that were closed down due to either poor ticket sales or censorship issues with the establishments of the time, despite the fact that many high-ranking officials attended these plays. Diamond Lil, about a racy woman in the 1890s, was her first major Broadway success, and was the basis for her character Lady Lou in her 1933 film She Done Him Wrong.