Prince Mikołaj Krzysztof Radziwiłł (; 2 August 1549 – 28 February 1616), nicknamed "the Orphan" (, ), was a Polish–Lithuanian nobleman (szlachcic), ordynat of Nyasvizh from 1586, Court Marshal of Lithuania from 1569, Grand Marshal of Lithuania from 1579, castellan of Trakai from 1586, voivode of Trakai Voivodeship from 1590, voivode of Vilnius Voivodeship from 1604, and governor of Šiauliai. After the treaty at Vienna in 1515, all Radziwills were Imperial Princes and he held a position as Imperial Prince of the Holy Roman Empire.
Biography
He was nicknamed "the Orphan", in his infancy, by the Polish king and Lithuanian grand duke Sigismund II Augustus (while his parents were still alive). He married Halaszka Eufemia Wiśniowiecka on 24 November 1584, a Calvinist, who under his influence, converted to Roman Catholicism.
He took part in the Livonian War against Muscovite forces. In 1573, he was a member of a diplomatic mission to France to the future king of Poland and grand duke of Lithuania, Henry III of France.
Unlike many other members of Radziwiłł family he tried to stay away from politics, especially from the dynastic clan politics of some of other Radziwiłłs like Janusz Radziwiłł; he also supported the forces loyal to the king and Polish–Lithuanian Commonwealth during the Zebrzydowski Rebellion, a szlachta's confederation threatening the king. and later translated into Polish.
While in Rome, he met Piotr Skarga and Stanislaus Hosius, who convinced him to convert from Calvinism to Catholicism, as later did his other brothers, many upon his insistence.