Leighton Goldie McCarthy PC (15 December 1869 – 3 October 1952) was a Canadian lawyer, politician, businessman and diplomat.

[1] He was elected to the House of Commons of Canada in 1898 as an independent representing the riding of Simcoe North, following the death of the incumbent, his father Dalton McCarthy, in a carriage accident.

From 1941 to 1944, McCarthy served as Canada's top diplomatic representative in Washington, D.C., and he became the first Canadian ambassador to the United States (previously, the position was called Envoy Extraordinary and Minister Plenipotentiary).

McCarthy was a lawyer before and after his political and diplomatic appointment but ended his practice in 1946.

McCarthy moved to Toronto and built a house at 45 Walmer Road in 1932,[3] and he died here in 1952.