Anglo-Norman family, afterward earls of March and Ulster, that wielded great power on the Welsh marches, attained political eminence in the 13th and 14th centuries, and in the 15th possessed a claim to the English throne. Among the most notable members of the family were Roger Mortimer (d. 1330), Earl of March; Edmund (d. 1381), 3rd earl, husband of Philippa, daughter and heiress of Lionel of Antwerp, Duke of Clarence (second surviving son of Edward III); and his grandson Edmund (d. 1425), 5th earl, who had by the laws of ordinary descent a better claim to the throne than Henry IV, son of Edward III's third surviving son, John of Gaunt, but nevertheless remained loyal to him. At Edmund's death the male line of the Mortimers became extinct.