William Joseph Stewart (September 20, 1894 - February 14, 1964) was an American coach and sports official who was an ice hockey referee and coach, and also an baseball umpire in Major League Baseball. In his first season as head coach of the Chicago Black Hawks, he led the team to a Stanley Cup championship in 1938. Born in Fitchburg, Massachusetts, he was the first American-trained head coach to win the Stanley Cup. He was also an umpire in the National League from 1933 to 1954, and officiated in four World Series.