Jeremi Wiśniowiecki, Polish nobleman (b. 1612)
Prince Jeremi Wiśniowiecki (Ukrainian: Ярема Вишневецький – Yarema Vyshnevetsky; 1612 – 20 August 1651) nicknamed Hammer on the Cossacks (Polish: Młot na Kozaków), was a notable member of the aristocracy of the Polish–Lithuanian Commonwealth, Prince of Wiśniowiec, Łubnie and Chorol 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 in 1646. His conversion from Eastern Orthodoxy to Roman Catholicism caused much dissent in Ruthenian (Ukrainian) lands (part of the Polish–Lithuanian Commonwealth). Wiśniowiecki was a successful military leader as well as one of the wealthiest magnates of Poland, ruling over lands inhabited by 230,000 people.