Donald Alexander MacKinnon (22 February 1863 – 20 April 1928) was a Canadian teacher, lawyer, politician, author, and the eighth Lieutenant Governor of Prince Edward Island from 1904 to 1910.Born in Uigg, Prince Edward Island, the son of William and Catherine Nicholson Mackinnon, MacKinnon attended Uigg grammar school and started teaching when he was 14. He later received a first-class teaching licence from the Prince of Wales College in Charlottetown.