Seymour James Farmer (June 20, 1878 – January 16, 1951) was a politician in Manitoba, Canada. He served as Winnipeg MLA from 1922 to 1949. During this time he also served as mayor of Winnipeg 1923-1924 and later as city councillor in the late 1920s and in the 1930s. He was the leader of the Manitoba Co-operative Commonwealth Federation from 1935 to 1947. He served as a cabinet minister in Manitoba's World War I coalition government. Farmer supported the Winnipeg General Strike. After the strike's end, he ran unsuccessfully for mayor in 1919 and 1920.