Joseph Octave Mousseau (April 25, 1844 – December 13, 1898) was a physician and political figure in Quebec. He represented Soulanges in the Canadian House of Commons from 1891 to 1892 as an Independent member.He was born in Berthier, Canada East, the son of Louis Mousseau, who was the son of Alexis Mousseau, and Sophie Duteau, dit Grandpré. Mousseau was educated at Montreal and Nicolet. He served on the town council for Saint-Polycarpe and also served as mayor.