Margaret Stewart (born c. 1455/1456 - c. 1480/1500?) was the younger daughter of James II of Scotland and Mary of Guelders. Once engaged to the Lancastrian Prince of Wales, Margaret instead became the mistress of William Crichton, 3rd Lord Crichton (an enemy of her brother, James III), and the mother of his illegitimate daughter, Margaret Crichton, later Countess of Rothes, and possibly his son, Sir James Crichton, progenitor of the Viscounts of Frendraught. Margaret and Lord Crichton may have been married later, after the death of Crichton's wife.