Anna Jagiellon (, ; 1523–1596) was Queen of Poland and Grand Duchess of Lithuania in her own right 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. After the death of King Sigismund II Augustus, her brother and the last male member of the Jagiellon dynasty, Anna's hand was sought by pretenders to the Polish–Lithuanian throne to maintain the dynastic tradition. She was elected, along with her then-fiancé Stephen Báthory, as co-ruler in the 1576 royal election of the Polish–Lithuanian Commonwealth. 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 House of Vasa on the Polish–Lithuanian throne for the next eighty years (1587–1668).