Henry II or Henry of Trastámara, 1333?-1379, Spanish king of Castile and León (1369-79), illegitimate son of Alfonso XI. After taking part in several unsuccessful revolts against his half brother, Peter the Cruel, he secured the aid of Du Guesclin and Peter IV of Aragón and drove Peter from the throne in 1366. Peter allied himself with England and, with the help of Edward the Black Prince defeated Henry at Nájera (1367), but after Edward's departure, Henry defeated and killed Peter at Montiel (1369). John of Gaunt, son-in-law of Peter the Cruel, and Ferdinand I of Portugal unsuccessfully contested his title as king and the succession of his son, John I.