Anna Jagiellon (Polish: Anna Jagiellonka, Lithuanian: Ona Jogailaite; 18 October 1523 – 12 November 1596) was Queen of Poland and Grand Duchess of Lithuania from 1575 to 1586.
She was a daughter of Polish King Sigismund I the Old and his Italian wife Bona Sforza.
Despite multiple proposals, she remained unmarried until the age of 52.
Their marriage was a formal arrangement and distant.
Báthory was preoccupied with the Livonian War, while Anna spent her time in Warsaw on local administrative matters and several construction works.
After Báthory's death in December 1586, she had an opportunity to claim the throne for herself (she was co-ruler and not merely a consort), but did not even attempt it.
Instead, she promoted her nephew Sigismund III Vasa, establishing the House of Vasa on the Polish throne for the next eighty years (1587–1668).