Adolph John "Otto" Rettig (January 29, 1894 – June 16, 1977) was a Major League Baseball pitcher who played in 1922 with the Philadelphia Athletics. He started four games, going 1-2 with a 4.91 ERA, walking 12 batters. He pitched 18 and one-third innings. He was part of the selected group of Major League Players to play at Wahconah Park.