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 House of Commons of Canada 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 practised in DeLorimier, near Montreal.
He was elected to the House of Commons for St.
Johns—Iberville in the by-election called after his brother was appointed a judge.
A Liberal, he was re-elected in 1908, 1911, 1917, and 1921.
He resigned in 1922, when he accepted of an office of emolument under the Crown.