Domhnall (or Donald) II of Mar (c. 1302 in Saline, Fife – 11 August 1332) was Regent of Scotland for just over a week during the minority of David II. His father was Gartnait, Earl of Mar, and his mother was Christina Bruce, sister of Robert I of Scotland. In 1332 the regent, Thomas Randolph, 1st Earl of Moray, died. On 2 August Domhnall was elected as the new regent at a meeting of the Scottish nobles at Perth. Through his marriage to Isabella Stewart they had a son Thomas, and a single daughter, Margaret, who succeeded her brother and became in her turn Countess of Mar.