Guillaume Gamelin Gaucher (August 16, 1810 – September 16, 1885) was a Quebecois businessman and political figure. He represented Jacques-Cartier in the 1st Canadian Parliament as a Conservative member. He was born Jean-Guillaume Gaucher in Sault-Saint-Louis (later (Kahnawake) in 1810 and was educated there. He became a merchant at Sainte-Geneviève on the Island of Montreal. Gaucher served as a lieutenant-colonel in the local militia and was also a justice of the peace. He was mayor of the parish of Sainte-Geneviève in 1845 and again from 1859 to 1863 after it became a village. He was elected to the Legislative Assembly of the Province of Canada for Jacques-Cartier in an 1864 by-election; he was elected again after Confederation. He died at Sainte-Geneviève in 1885.