Konstanty Wasyl Ostrogski

Konstanty Wasyl Ostrogski (2 February 1526 – 13 or 23 February 1608, also known as Kostiantyn Vasyl Ostrozkyi, , , ) was a Ruthenian Orthodox magnate of the Polish–Lithuanian Commonwealth, a prince, starost of Volodymyr, marshal of Volhynia and voivode of the Kiev Voivodeship. Ostrogski refused to help False Dmitriy I and supported Jan Zamoyski. The date of birth of Konstanty Wasyl Ostrogski is disputed. According to some historians he was born around 1524/1525. He was born probably in Turów. In the 1570s he waged a war against another magnate, Stanisław Tarnowski, about disputed possession of estates in the area of Tarnów, in Lesser Poland.