Zasławski
The House of Zasławski (plural Zasławscy) was the name of a Polish–Ruthenian noble family and a cadet branch of the Ostrogski family. The Zasławski family had its power base in Volhynia, Crown of the Kingdom of Poland (today in Ukraine), and traced its origins to a branch of the Rurikids that took its name from the Iziaslav. Due to their relation to the Rurikids, the Zasławski family held the title of Knyaz (prince).