William Henry Dinneen, alternately spelled Dineen (April 5, 1876 – January 13, 1955), was an American right-handed pitcher in Major League Baseball who followed his 12-year career from 1898 to 1909 with a highly regarded tenure as an American League umpire from 1909 to 1937. Dinneen was the plate umpire for baseball's first All-Star Game.