Mary MacDuff, Countess of Fife (née de Monthermer; October 1297 – c. 1371) was an English noblewoman.
In early 1297, her mother faced the intense disapproval of King Edward when she decided to secretly marry Ralph de Monthermer, a squire in her household.
[3][4] Joan is said to have told her father that if it was no disgrace for an earl to marry a poor woman, it should not be blameworthy for a countess to advance a capable young man.
[5] Mary also had four half-siblings from her mother's first marriage to Gilbert de Clare, 6th Earl of Hertford.
[6] In 1332, Mary and her daughter were captured at Perth by supporters of King David II of Scotland.
In 1346, Mary's husband was tried for treason and sentenced to a traitor's death by Edward III of England.