Barbara Giza

Barbara Giza (; c. 1550 – May 1589), was a mistress of King Sigismund II Augustus of Poland during 1570–72. She was a daughter of a Warsaw burgher Jan Giza, a merchant and usurer, and his wife Anna, whose origins are unknown.

Barbara was a Protestant, and she is sometimes given credit for influencing the King towards religious tolerance of Protestants.

Near the end of King Sigismund II Augustus' life, after the death of his wife, he expressed a desire to marry Barbara with the hope of producing an heir. However, he died before a marriage could take place. Provided by Wikipedia