Nicholas I (Czech: Mikuláš I. Opavský) (c. 1255 – 25 July 1318) was the natural son of Bohemian king Ottokar II Přemysl[1] and his mistress Agnes of Kuenring.
As his half-brother Wenceslaus II was designated to succeed his father on the Bohemian throne, Nicholas in compensation received Troppau, then a part of the Moravian march.
He supported his father in the 1278 Battle on the Marchfeld, was captured by Hungarian forces, but regained his duchy from the victorious German king Rudolf of Habsburg.
His rule was however challenged by Ottokar's widow Kunigunda of Halych, who had retired to Hradec nad Moravicí.
They had three sons: Nicholas retained the Duchy of Opava after the last Přemyslid ruler of Bohemia, King Wenceslaus III was killed in 1306.