Alexander de Brus (c. 1285 – 9 February 1307), Dean of Glasgow, was a younger brother of King Robert I of Scotland, who supported his brother in the struggle for the crown of Scotland. He was captured by forces at Loch Ryan, Galloway, Scotland and later executed as a traitor.
Born c. 1285 at Carrick, Ayrshire, Scotland a son of Robert de Brus, 6th Lord of Annandale and Margaret, Countess Of Carrick. While leading an invasion force with his brother Thomas de Brus consisting of eighteen galleys, landing at Loch Ryan. The invasion force was quickly overwhelmed by local forces, led by Dungal MacDouall, who was a supporter of the Comyns and he and his brother were captured. He was later beheaded on 9 February 1307 in Carlisle, Cumberland, England.