Mary de Monthermer 14th-century English noblewoman (1297–1371) Parents Ralph de Monthermer Joan of Acre Children Isabella, Countess of Fife Siblings Margaret de Clare Elizabeth de Clare Gilbert de Clare, 8th Earl of Gloucester Thomas de Monthermer, 2nd Baron de Monthermer Eleanor de Clare Edward de Monthermer, 3rd Baron Monthermer Joan de Monthermer Partners Donnchadh IV, Earl of Fife