Louis-Joseph Gauthier, KC (March 21, 1866 – April 12, 1938) was a lawyer and political figure in Quebec.

He represented L'Assomption in the Legislative Assembly of Quebec from 1906 to 1908 and St. Hyacinthe and then St. Hyacinthe—Rouville in the House of Commons of Canada from 1911 to 1921 as a Liberal.

Gauthier was admitted to the Quebec bar in 1889 and practised in Montreal, Laurentides and Westmount.

He was elected to the Quebec assembly in a 1906 by-election held after Joseph-Édouard Duhamel resigned his seat to accept an appointment.

He died in Montreal at the age of 72 and was buried in the Notre Dame des Neiges Cemetery.