John "Jocko" Milligan (August 8, 1861 – August 29, 1923) was an American professional baseball player who played catcher in Major League Baseball from 1884 to 1893. He played for the Philadelphia Athletics, St. Louis Browns, Philadelphia Athletics, Washington Senators, Baltimore Orioles, and New York Giants. In 772 games over 10 seasons, Milligan posted a .286 batting average (848-for-2964) with 440 runs, 189 doubles, 50 triples, 49 home runs, 497 runs batted in, 210 bases on balls, .341 on-base percentage, and .433 slugging percentage.