Alexander Grant MacKay (March 7, 1860 – April 25, 1920) was a Canadian teacher, lawyer and provincial level politician.

He attended post secondary studies at the Owen Sound College and the University of Toronto obtaining a Master of Business degree.

MacKay began his political career on the municipal level with his election to the Owen Sound Board of Education in 1894.

MacKay moved to Alberta in the spring of 1912, he was accused by the Toronto press of leaving Ontario because he was unable to get along with new Liberal opposition leader Newton Rowell.

MacKay ran in the Edmonton electoral district and was defeated finishing a very close 3rd place in the block vote.