James E. Day (born July 7, 1946, in Thornhill, Ontario) was a Canadian Olympic equestrian show jumping champion[1] and Thoroughbred horse trainer.

Day first joined the Canadian Equestrian Team in 1964, and in 1966 tied the record high jump of 7 feet 1 inch at the National Horse Show in New York.

[2] In 1968, he was a member of Canada's gold-medal equestrian team at the Summer Olympics in Mexico City.

[1] In 1971, Day took a job training race horses for Ernie Samuel, who had recently founded Sam-Son Farm.

Day assisted in building the operation into a top Thoroughbred racing and breeding facility over the next 25 years.