John Horne Blackmore (March 27, 1890 - May 2, 1971) a school teacher and principal by training, was the first leader of the Social Credit Party of Canada. Blackmore became leader of the party in 1935 and was first elected to the Canadian House of Commons in the 1935 Canadian election as Member of Parliament representing Lethbridge, Alberta. Blackmore remained party leader until 1944 and remained an MP until he was defeated in the 1958 Canadian election in which Social Credit lost all of its MPs.