Alexander MacDonald (c. 1736 – 9 September 1791) was a Roman Catholic bishop who served as the Vicar Apostolic of the Highland District, Scotland.
Born in Bornish, South Uist in about 1736, he was ordained a priest on 10 August 1764.
He was appointed the Vicar Apostolic of the Highland District and Titular Bishop of Polemonium by the Holy See on 30 September 1779.
The principal consecrator was Bishop George Hay, and the principal co-consecrator was Bishop Alexander Cameron.
In 1783, he moved the seminary for the Highland District to Samalaman House.