Olyka Castle, located in Olyka, Ukraine was the principal seat of the Radziwill princely family in Volhynia from 1564 until the late 18th century. The founder of the castle was Prince Mikołaj "the Black" Radziwiłł (1515–1565) who gave Olyka to his youngest son Stanisław. Two senior branches of the Radziwill family were based in Nesvizh and Kletsk.