Macdonald "Mac" Benson (born June 30, 1930, in Wilmington, Delaware) is a Canadian Horse Racing Hall of Fame trainer.
Mac Benson embarked on his professional training career in 1958 and began by working for prominent Delaware Thoroughbred owner, William du Pont, Jr.
Among his clients in the early 1970s was another duPont family member, Bayard Sharp, who was a founding director of Delaware Park Racetrack and a former president of The Blood-Horse Inc. magazine.
Settling in the Toronto area in 1978, Mac Benson met with instant success as head trainer of the E. P. Taylor racing stable.
He remained with Windfields Farm through the death of E. P. Taylor in 1989 and would later train for American George W. Strawbridge, Jr. and Robert J. Costigan of Vancouver, British Columbia.