Michael Joseph Sullivan (October 23, 1866 – June 14, 1906) was an American professional baseball player. He played in Major League Baseball as a right-handed pitcher from 1886 to 1899 for the Washington Nationals (1889), Chicago Colts (1890), Philadelphia Athletics (1891), New York Giants (1891 and 1896–97), Cincinnati Reds (1892–93), Washington Senators (1894), Cleveland Spiders (1894–95) and the Boston Beaneaters (1899). He led the National League in win–loss percentage (.750) in 1892. Sullivan died in his hometown at the age of 39.