John George MacKay (November 6, 1893 – October 21, 1974) was a farmer and political figure on Prince Edward Island. He represented 4th Prince in the Legislative Assembly of Prince Edward Island from 1949 to 1966 as a Liberal. MacKay was the 20th Lieutenant Governor of Prince Edward Island, serving from October 6, 1969 to October 24, 1974.He was born in Albany, Prince Edward Island, the son of David MacKay and Almira Harvey, and was educated there. MacKay married Muriel Beatrice Boulter in 1918.