RADZIWIŁŁ. — An ancient noble family of Lithuanian origin, united in the 16th century by kinship ties with the Jagiellonians. Its progenitor was Ostyk, but it was his son R. Ostykowicz, palatine of Troki and castellan of Wilno, who gave his name to the family.
In the 16th century, a large part of the family members adhered to the Reformation. A prominent representative was NICHOLAS, called the Black (1515–65), marshal and grand chancellor of the Grand Duchy of Lithuania, trusted advisor to Sigismund Augustus, King of Poland, who in 1547 received the title of Prince of the Empire, a dignity also confirmed for Poland in 1569. He was a supporter of the Calvinists and had the Bible published in 1563 in a translation by Socinians. His son NICHOLAS CHRISTOPHER (1549–1616), influenced by Cardinal Hosius, converted to Catholicism and stood alongside King Sigismund III in introducing the Counter-Reformation in Poland. GEORGE (1556–1600), another son of NICHOLAS the Black, became a cardinal in 1586; MICHAEL CASIMIR (1625–80) held diplomatic posts (including an embassy to the Pope in 1679). In the 19th century, EDMUND (1842–95), a member of the German Centre Party and deputy, later took the Benedictine habit at Beuron.