Michael Joseph "King" Kelly (December 31, 1857 – November 8, 1894) was an American right fielder, catcher, and manager in various professional American baseball leagues including the National League, International Association, Players' League, and the American Association. He spent the majority of his 16-season playing career with the Chicago White Stockings and the Boston Beaneaters. Kelly was a player-manager three times in his career – in 1887 for the Beaneaters, in 1890 leading the Boston Reds to the pennant in the only season of the Players' League's existence, and in 1891 for the Cincinnati Kelly's Killers – before his retirement in 1893. He is also often credited with helping to popularize various strategies as a player such as the hit and run, the hook slide, and the catcher's practice of backing up first base.