Beatrice of Castile

Beatrice of Castile (1254–1286) was a daughter of Alfonso X of Castile and Violant of Aragon, born at Valladolid. Alfonso first betrothed her to John II, Margrave of Brandenburg, to win Brandenburg's support for his claim to the German crown, but the engagement was broken off. In August 1271 she married at Murcia William VII, Marquess of Montferrat, becoming his third wife.

Her children included Yolande, who took the name Irene and married the Byzantine emperor Andronikos II Palaiologos, and John I, who succeeded William as marquess. She died in 1286, six years before her husband.