Casimir IV Jagiellon, Grand Duke of Lithuania from 1440 and King of Poland from 1447 (b. 1427)
Casimir IV (in full Casimir IV Andrew Jagiellon; Polish: Kazimierz IV Andrzej Jagiellończyk [kaˈʑimi̯ɛʒ jaɡi̯ɛlˈlɔɲt͡ʃɨk] (listen); Lithuanian: Kazimieras Jogailaitis; 30 November 1427 – 7 June 1492) was Grand Duke of Lithuania from 1440 and King of Poland from 1447, until his death. He was one of the most active Polish-Lithuanian rulers, under whom Poland, by defeating the Teutonic Knights in the Thirteen Years' War recovered Pomerania, and the Jagiellonian dynasty became one of the leading royal houses in Europe.

The great triumph of his reign was bringing Prussia under Polish rule. The rule of Casimir corresponded to the age of "new monarchies" in western Europe. By the 15th century Poland had narrowed the distance separating it from western Europe and become a significant factor in international relations. The demand for raw materials and semi-finished goods stimulated trade, producing a positive balance, and contributed to the growth of crafts and mining in the entire country. He was a recipient of the English Order of the Garter (KG), the highest order of chivalry and the most prestigious honour in England.

Following Casimir's death in 1492, John I Albert succeeded him as King of Poland, and Alexander Jagiellon was proclaimed Grand Duke of Lithuania.