Sidney Earle Smith PC QC (9 March 1897 – 17 March 1959) was an academic and Canada's Secretary of State for External Affairs in the government of Prime Minister John Diefenbaker.

Born and raised on Nova Scotia's Port Hood Island, Smith grew up speaking both English and Gaelic. He received a B.A. and an M.A. from the University of King's College, followed by an LL.B. from Dalhousie University.^[1]

Smith became a lawyer and a professor of law, lecturing at Osgoode Hall Law School and then at Dalhousie University. In 1929, he became dean of Dalhousie's law school. In 1934, he left the Maritimes to become president of the University of Manitoba. In 1945, he was appointed the president of the University of Toronto. He remained in that role for twelve years, overseeing a major period of the university's expansion.

A strong Conservative in the Red Tory tradition, Smith became a prominent member of the Progressive Conservative Party. In 1956, he was considered a possibility for the party's leadership, but decided not to run, disappointing those in the party establishment who wished to prevent the populist John Diefenbaker from becoming leader.

After Diefenbaker won a surprise minority government in 1957, Smith was appointed as Secretary of State for External Affairs. Despite Smith's brilliance and popularity in academia, his success in this new role was limited. After holding the position for two years, he died suddenly of a stroke in 1959.

Sidney Smith Hall, the central building of the Faculty of Arts and Science at the University of Toronto, is named after him.