Ladislaus II or Ladislaus Jagiello (yägyĕ´lō), 1350?–1434, king of Poland (1386–1434), grand duke of Lithuania (1378–1401), founder of the Jagiello dynasty. Leaguing with Poland against the menacing Teutonic Knights, he acceded to the Polish throne by marrying Queen Jadwiga. Baptized at this time, he agreed to convert Lithuania to Christianity. The union of Poland and Lithuania continued after he delegated (1401) a cousin as grand duke. Jagiello's victory over the Teutonic Knights at Tannenberg (1410) resulted in the First Peace of Toruń in 1411. His son by a later wife, Ladislaus III, succeeded him as Polish king.

Ladislaus IV, 1595–1648, king of Poland (1632–48), son and successor of Sigismund III. His reign was marked by struggles with his subjects and wars with the Swedes, the Russians, and the Ottomans. Ladislaus in his later years vainly sought to establish authority over the nobles. The Cossack revolt, under Chmielnicki, broke out just before his death. He was succeeded by his brother, John II.

Ladislaus IV, 1262–90, king of Hungary (1272–90), son and successor of Stephen V. Ladislaus became unpopular by favoring the Cumans, from whom he was descended through his mother. During his reign, much of it while he was a minor, the magnates and lower nobility were able to establish their power constitutionally, at the expense of the monarchy. There were several revolts against the king, and he was finally slain by the once-favored Cumans. He died heirless; his successor, Andrew III (reigned 1290–1301), who issued from another branch of the Arpad dynasty, was succeeded as king of Hungary by King Wenceslaus III of Bohemia.