Harry Mitchell Grabiner (December 26, 1890 – October 24, 1948) was an American professional baseball executive. A 40-year employee of the Chicago White Sox, he served the team's owners—founding president Charles Comiskey, son and successor J. Louis Comiskey, and Lou’s widow, Grace—in a number of capacities, rising from peanut vendor to club secretary, business manager and vice president. He is often listed as the White Sox' first general manager, with a term lasting from as early as 1915 through 1945. After leaving the White Sox after the 1945 season, he joined Bill Veeck’s ownership syndicate and became a vice president and minority stockholder with the Cleveland Indians from 1946 until his death in 1948.
As team secretary and top aide to Charles Comiskey, Grabiner was a management eyewitness to the 1919 Black Sox Scandal, in which eight White Sox players conspired with gamblers to lose the 1919 World Series.
Eighteen years after Grabiner’s death, Veeck revealed in his 1966 book The Hustler’s Handbook that he had discovered a diary Grabiner wrote of the 1919 season. In the chapter “Harry’s Diary,” Veeck quotes from Grabiner’s document and writes, “Beyond any doubt, the White Sox front office had more than some inkling of what was going on from the very first game of the 1919 World Series.” Some accounts state that Grabiner warned Comiskey, American League president Ban Johnson and National League president John Heydler of a possible game-fixing scandal after Game 2 of the Series, but he was ignored.