Isabel de Beaumont, Duchess of Lancaster, of the House of Brienne (c. 1318 – 1361) was an English noblewoman.
[1] Her maternal grandparents were Alexander Comyn, Sheriff of Aberdeen and Joan le Latimer.
She married Henry of Grosmont, 1st Duke of Lancaster in 1330, but lived apart from her husband for a few years before consummation of the marriage due to her age.
[1] Isabel accompanied her husband on some of his diplomatic travels to the continent, such as to the Low Countries in 1341 and Gascony in 1345.
With her husband, Isabel founded the College of the Annunciation of St Mary in the Newark, Leicester.