Herzogtum Ratibor
John I of Opava-Ratibor (; ; – ) was the founder the Opava branch of the Bohemian Přemyslid dynasty, which lasted until 1521. In 1365, he became the sole heir of the Duchy of Racibórz. From 1367 to 1377 he ruled the Duchy of Opava () jointly with his brothers, Nicholas III, Wenceslaus I and Przemko I. From 1377 until his death, he was also Duke of Krnov and Bruntál.