Sir Donald Alexander Macdonald CMG ISO (October 31, 1845 – May 4, 1920) was a Canadian Militia officer.
After the 2nd Cornwall Rifle Company was incorporated into the newly formed 59th Stormont and Glengarry Battalion of Infantry, Macdonald was appointed as adjutant in 1869, promoted to major in 1871 and lieutenant-colonel in 1877.
Macdonald would see active service with the militia during the Fenian raids of 1866, the Red River expedition of 1870, and the North-West Rebellion of 1885.
In 1874, he joined the stores branch of the Department of Militia and Defence.
He was responsible for equipping the first Canadian formations raised in World War I.