Thomas Kerr Slack (February 19, 1875 – November 1, 1956) was an Ontario farmer and political figure. He represented Dufferin in the Legislative Assembly of Ontario from 1919 to 1923 as a United Farmers member and from 1926 to 1934 as a Progressive member.He was born in Melancthon Township, Dufferin County, Ontario, the son of Richard Slack, an immigrant from Ireland, and Elizabeth Silk. In 1905, he married Margaret Brown. Slack served as clerk for Melancthon township.