Mikołaj Krzysztof Radziwiłł, nicknamed The Black, was a Polish-Lithuanian noble who held several administrative positions within the Grand Duchy of Lithuania: Voivode of Vilnius, Grand Lithuanian Chancellor, and Grand Hetman of Lithuania.
Alternate renditions of his name include Lithuanian: Mikalojus Radvila Juodasis, Belarusian: Мікалай Радзівіл Чорны, and Latin: Nicolaus Radvil. His first name is sometimes given in English as Nicholas.