Kuka naimisissa Marie Sidonie Těšínská?

Frederick IV, Duke of Legnica (20 April 1552 – 27 March 1596) was Duke of Legnica from 1571 until his death (as a co-ruler of his elder brother during 1571–1576 and 1580–1581).

He was the third but second surviving son of Frederick III, Duke of Liegnitz, by his wife Katharina, daughter of Henry V, Duke of Mecklenburg. He was named after his brother Frederick, who died in 1551, one year before his birth.