Augustine "Austin" Colin Macdonald was born 30 June 1837 the son of Hugh and Catherine Macdonald.. He was a partner in the firm MacDonald Bros. & Co., a retail general merchandise enterprise in Montague Bridge, Prince Edward Island. He was elected to the Legislative Assembly as the member for third Kings in September 1870 and to the federal House of Commons as the member for Kings in 1873. In the latter capacity he served a couple of terms between 1873 and 1896. He was appointed Lieutenant-Governor of Prince Edward Island on 2 June 1915 and died in office on 16 July 1919. During World War I, he offered the use of Government House as a hospital for convalescing veterans. A.C. Macdonald was married to Mary Elizabeth MacDonald, daughter of John S. MacDonald of Charlottetown on 27 June 1865. The couple had three sons and four daughters. One daughter, Josephine, married Roderick James Macdonald.

Augustine "Austin" Colin Macdonald, youngest child of Hugh Macdonald (1788-1857) and Catherine Kennedy Macdonald (ca. 1795-1872), was born 20 June 1837 in Panmure Island, Prince Edward Island. He married Mary Elizabeth MacDonald (16 February 1840 - 1 February 1918) on 27 June 1865. They had seven children: M. Josephine (b. 1867), W. Jane (b. 1869), S. Francis (b. 2 July 1871), C. Helena (b. 2 May 1874), A. Florence (b. 1878), A. J. Louis (b. 1880), and A. Ernest (b. 17 February 1883). Daughter Josephine married Roderick James Macdonald.

Austin was involved in the firm of A. A. Macdonald and Bros. with his brothers Andrew Archibald and Archibald John and engaged in a range of business activities through the family business. He was also involved in local politics, representing the 3rd district of Kings County in the Legislative Assembly as a Conservative from 1879 to 1873. Austin was a Member of Parliament for Kings County from 1873 to 1874, 1878 to 1886, and 1892 to 1896. He was appointed Lieutenant Governor of Prince Edward Island in 1915. Austin died in office on 16 July 1919.