Joseph Pierre Dumas (February 19, 1875 – January 14, 1950) was a politician in Manitoba, Canada. He served in the Legislative Assembly of Manitoba from 1915 to 1920 as a member of the Liberal Party. Born in Neche, North Dakota, Dumas came to Manitoba in 1897. He worked as a construction contractor. In 1898, he married Mary Nisbett. Dumas was elected to the Manitoba legislature in the 1915 provincial election, defeating a Conservative and an independent Liberal candidate in the constituency of St. Boniface. The Liberal Party won this election, and Dumas served as a backbench supporter of Tobias Norris's administration for the next five years. He ran for re-election in the 1920 campaign, but finished third against Conservative-Independent candidate Joseph Bernier. In 1935, Dumas moved to California. He died in Saugus, California.