Henri-Louis Gagnon (September 13, 1881 – June 16, 1964) was a Canadian politician.
Born in Lambton, Quebec, the son of Louis Gagnon and Sobronie Bélanger, Gagnon was elected to the Legislative Assembly of Quebec for Frontenac in 1931. A Liberal, he was defeated in 1935. He was mayor of Lambton in 1935 and 1936. He was re-elected in 1939 and defeated in 1944.[1]