Domhnall II, Earl of Mar (1293 – 11 August 1332) was Regent of Scotland for just over a week during the minority of David II, King of Scotland.
Domhnall's father was Gartnait, Earl of Mar. His mother's identity is uncertain, although she seems to have been an elder daughter of Robert Bruce, Earl of Carrick.
It appears likely that he fought on the side of Edward II of England at the Battle of Boroughbridge in March 1322, as it is recorded that afterwards the Earl of Mar took Bartholomew de Badlesmere, who was one of Edward's captured opponents, to Canterbury.
In 1332 the regent of Scotland, 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.
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.