Catherine Jagiellon, queen of John III of Sweden (d. 1583)
Catherine Jagiellon (Polish: Katarzyna Jagiellonka; Swedish: Katarina Jagellonica, Lithuanian: Kotryna Jogailatė; 1 November 1526 – 16 September 1583) was a Polish princess and Queen of Sweden as the first wife of King John III. As such, she was also Duchess of Finland (1562–1583) and Grand Princess of Finland (1581–1583). Catherine had significant influence over state affairs during the reign of her spouse and negotiated with the pope to introduce a counter-reformation in Sweden. She was the mother of the future Sigismund III Vasa, King of Poland.