Jeremi Wiśniowiecki
Prince Jeremi Michał Korybut Wiśniowiecki, nicknamed Hammer on the Cossacks (Polish: Młot na Kozaków), was a notable member of the aristocracy of the Polish–Lithuanian Commonwealth, Prince of Vyshnivets, Lubny and Khorol in the Crown of the Kingdom of Poland and the father of the future King of Poland, Michael I. A notable magnate and military commander with Ruthenian and Moldavian origin, Wiśniowiecki was heir of one of the biggest fortunes of the state and rose to several notable dignities, including the position of voivode of the Ruthenian Voivodship (today Poland and Ukraine) in 1646. His conversion from Eastern Orthodoxy to Roman Catholicism caused much dissent in Ruthenian lands (part of the Polish–Lithuanian Commonwealth).