Donald Alexander Macdonald, PC (February 17, 1817 – June 10, 1896) was a Canadian politician. Born in 1817 in St. Raphael's, Upper Canada, Donald Alexander Macdonald studied at under the first Catholic Bishop of Ontario, Alexander Macdonell. He became a railway contractor and was elected as a member of the Legislative Assembly of the Province of Canada from 1857 to 1867. He was the Liberal Member of Parliament for Glengarry in the House of Commons of Canada from 1867 to 1875, and served as Postmaster General of Canada. In 1875 Macdonald was appointed the fourth Lieutenant Governor of Ontario and held that post until 1880. He died in Montreal in 1896.