Sigismund II, also known as Sigismund II Augustus, was the last king of the Jagiellonian dynasty in Poland and Grand Duke of Lithuania. He ruled from 1548 until his death in 1572. His reign is noted for the political union of Poland and Lithuania, which led to the establishment of the Polish-Lithuanian Commonwealth. During his rule, Sigismund II promoted the arts and culture, fostering the Renaissance in his realm. He was also known for his efforts to strengthen the central authority of the monarchy, although his reign faced challenges from the nobility and external threats.