John II Casimir (Polish: Jan II Kazimierz Waza; German: Johann II.

Kasimir Wasa; Lithuanian: Jonas Kazimieras Vaza (22 March 1609 – 16 December 1672) is King of Poland and Grand Duke of Lithuania during the era of the Polish-Lithuanian Commonwealth, Duke of Opole in Upper Silesia, and titular King of Sweden 1648-1660.

His parents are Sigismund III Vasa (1566-1632) and Constance of Austria (1588-1631).

His older brother, and predecessor on the throne, is Władysław IV Vasa.

Related to the Habsburg rulers of the Holy Roman Empire he is the third and last monarch on the Polish throne from the House of Vasa.

He is the last ruler of Polish-Lithuanian Commonwealth bearing a dynastical blood of House of Gediminas and a branch of it, the Jagiellons, although from the female line.