Władysław III of Poland (31 October 1424 – presumably 10 November 1444), also known as Ladislaus of Varna, was King of Poland and Supreme Duke of the Grand Duchy of Lithuania from 1434, as well as King of Hungary and Croatia as Vladislaus I from 1440 until his presumed death at the Battle of Varna. He was the eldest son of Władysław II Jagiełło (Jogaila) and the Lithuanian noblewoman Sophia of Halshany.
Władysław succeeded his father shortly before turning ten in 1434 and was, therefore, deemed unfit to rule until coming of age. Cardinal Zbigniew Oleśnicki acted as regent and a temporary provisores council executed power in the king's name. However, Władysław's legitimacy to the crown was contested by Lesser Polish nobles favouring the candidacy of Siemowit V of Masovia, who was of Piast lineage. In the aftermath of the coronation, Spytko III of Melsztyn accused Oleśnicki, the council and the Catholic Church of exploiting the king's youth to hold authority. A sympathiser with the Czech Hussites, Spytko was killed at the Battle of Grotniki in 1439, thus ending the hostilities.