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 August 2 Domhnall was elected as the new regent at a meeting of the Scottish nobles at Perth.
Following the invasion of Edward Balliol, with the support of Edward III of England, Mar led the Scots loyalists to confront them. He was defeated and killed at the Battle of Dupplin Moor, only nine days after his election as regent.
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.
| Preceded by Gartnait |
Mormaer of Mar 1305–1332 |
Succeeded by Thomas |
| Preceded by Thomas Randolph, 1st Earl of Moray |
Regent of Scotland 2–11 August 1332 |
Succeeded by Sir Andrew Murray |