William Johnston Tupper KC (June 29, 1862 – December 17, 1947) was a politician and office holder in Manitoba, Canada. He served as the province's 12th Lieutenant Governor from 1934 to 1940. Tupper was born in Halifax, Nova Scotia, the son of Charles Tupper (who later served as Premier of Nova Scotia from 1863 to 1867, and Prime Minister of Canada in 1896) and Frances Amélia Morse. He was named in honour of his father's mentor James William Johnston. He was educated at Upper Canada College and Harvard Law School but returned to Nova Scotia to practice law, being called to the bar in 1885. Later in the same year, Tupper enlisted as a private in the Canadian army to assist in putting down the North-West Rebellion, and remained in Manitoba afterwards. He was called to the Manitoba Bar in 1886