Marie Joseph Demers (May 31, 1871 – July 28, 1940) was a Canadian politician.Born in St-Georges d'Henryville, Quebec, the son of Alexis-Louis Demers, former M.L.A. for Iberville, and the brother of Louis Philippe Demers, who sat in the Canadian House of Commons from 1900 to 1906 until he was appointed a Puisne Judge, Superior Court. Demers was educated at the College of St. Hyacinthe and St. Mary's College, Montreal. A lawyer, he practiced in DeLorimier, near Montreal.