John Joseph O'Brien (February 5, 1873 â June 10, 1933) was an American outfielder in Major League Baseball. Between 1899 and , O'Brien played with the Washington Senators in the National League (1899), and for the Washington Senators (1901), Cleveland Blues (1901), and Boston Americans (1903) of the American League. A native of Watervliet, New York, he batted left-handed and threw right-handed.
O'Brien spent part of two seasons with the Washington teams and Cleveland before moving to Boston. His most productive season came in 1899 as a rookie, he posted hit .282 and reached career-highs in home runs (6), RBI (51), runs (68), stolen bases (17) and games played (127). But he is best remembered as the first player to pinch-hit in a World Series game, when he struck out for Boston catcher Lou Criger in the 9th inning of Game One of the 1903 series against Pittsburgh. He was a .259 hitter in 326 games, including nine home runs with 133 RBI and 171 runs.
O'Brien died his homeland of Watervliet at the age of 60.