John K. Butler (1908–1964) was an American pulp writer who published detective stories in Black Mask, Detective Fiction Weekly, Double Detective and Dime Detective. Before writing fiction, he worked as a reader and editor at Universal Studios during the transition to sound films. His stories often featured working-class investigators with unusual jobs.

Butler’s best-known character was Steve Midnight, a Los Angeles cab driver who became a private investigator; the series appeared in Dime Detective. He also wrote stories about police detective Rex Lonergan and undercover officer Tricky Enright.