William Hamilton Merritt (July 3, 1793 – July 5, 1862) was a businessman and politician in the Niagara Peninsula of Upper Canada in the early 19th century. Although he was born in the United States, his family was Loyalist and eventually settled in Upper Canada. Merritt fought in the War of 1812, was captured by the invading American forces, and held as a prisoner of war. After the war, he returned to the Niagara region and began a career in business. He was one of the founders of the Welland Canal.