William Abraham Hewitt (May 15, 1875 – September 8, 1966) was a Canadian sports executive and journalist, also widely known as Billy Hewitt. He was secretary of the Ontario Hockey Association (OHA) from 1903 to 1966, and sports editor of the Toronto Daily Star from 1900 to 1931. He promoted the establishment of the Canadian Amateur Hockey Association (CAHA), then served as its secretary-treasurer from 1915 to 1919, registrar from 1921 to 1925, registrar-treasurer from 1925 to 1961, and a trustee of the Allan Cup and Memorial Cup. Hewitt standardized player registrations in Canada, was a committee member to discuss professional-amateur agreements with the National Hockey League, and negotiated working agreements with amateur hockey governing bodies in the United States. He oversaw referees within the OHA, and negotiated common rules of play for amateur and professional leagues as chairman of the CAHA rules committee. After retiring from journalism, he was the managing-director of Maple Leaf Gardens from 1931 to 1948, and chairman of the committee to select the inaugural members of the Hockey Hall of Fame in 1945.

Hewitt was a member of the Canadian Olympic Committee from 1920 to 1932, helped select athletes for the Summer and Winter Olympics, and was the head of mission for Canada at the 1928 Winter Olympics. He served as the financial manager for the Canada men's national ice hockey team which won Olympic gold medals in 1920, 1924, and 1928; while sending reports on the Olympic Games to Canadian newspapers. He introduced the CAHA rules of play to the Ligue Internationale de Hockey sur Glace in 1920, and refereed the first game played in the history of ice hockey at the Olympic Games. He also served on several committees for the Amateur Athletic Union of Canada, and including chairman of the registration committee which oversaw the reinstatement of professionals as amateurs.

In Canadian football, Hewitt managed the Toronto Argonauts from 1905 to 1907, served as vice-president of the Ontario Rugby Football Union, and helped organize the meeting which established the Inter-provincial Rugby Football Union in 1907. He was president of the Canadian Rugby Union from 1915 to 1919, sought to implement uniform rules of play across Canada, and was a referee for collegiate and inter-provincial games. In horse racing, Hewitt was a patrol judge at Woodbine Race Course, was a steward of the Incorporated Canadian Racing Association for 31 years, then a steward of the Ontario Racing Association for 14 years.

Hewitt was the father of radio sports announcer Foster Hewitt, and the grandfather of television sports commentator Bill Hewitt. Hewitt guided his son into radio, and together they called the 1925 King's Plate, the first horse race to be broadcast on radio. Later in life, Hewitt published his memoirs, had two arms broken in a car accident that killed his wife, and a heart attack while on a tour of Czechoslovakia with the Winnipeg Maroons. He was a life member of both the OHA and the CAHA, the guest of honour at two testimonial dinners, and multiple ice hockey trophies were named for him including the Dudley Hewitt Cup. He was inducted into the builder category of the Hockey Hall of Fame, the International Hockey Hall of Fame, and the IIHF Hall of Fame.