William Hamilton Merritt (3 July 1793 – 5 July 1862) was an influential figure in the Niagara Peninsula of Upper Canada in early 19th century and one of the fathers of the Welland Canal.
Merritt was born in Bedford in Westchester County, New York on July 3, 1793. His father, Thomas, fought as a United Empire Loyalist in the American Revolutionary War. After the revolution, the family resided in New Brunswick before returning to the U.S. In 1795, they moved to Upper Canada, settling on the Niagara Peninsula on the Twelve Mile Creek. Merritt attended school in Burlington, Ontario, studying mathematics and field surveying. Afterwards, he became a partner in a store at Shipman's Corners (now St. Catharines).
Just before the War of 1812, he sold his interest in the store and returned to his family's 200-acre (0.81 km2) farm on the creek. During the war, he joined the Second Lincoln Militia, stationed at Chippawa. He was a captain and leader of the volunteer dragoons throughout the war. During constant patrols along the Niagara River, an idea came to him for a canal to by-pass the Niagara Falls. He was captured during Battle of Lundy's Lane and held prisoner of war in Massachusetts until March 1815.