Sigismund I, also known as Sigismund the Old, was the King of Poland and Grand Duke of Lithuania from 1506 until his death in 1548. He was a member of the Jagiellonian dynasty and played a significant role in strengthening the Polish-Lithuanian Commonwealth. His reign is noted for cultural and economic development, as well as military successes against the Teutonic Knights. Under Sigismund I's leadership, the Commonwealth experienced a flourishing of the arts and sciences, with notable figures such as the astronomer Nicolaus Copernicus emerging during this period. He also worked to consolidate power and improve relations with neighboring states, contributing to the stability of the region.