Sigismund I the Old, Polish king (d. 1548)
Sigismund I the Old (Polish: Zygmunt I Stary, Lithuanian: Žygimantas II Senasis; 1 January 1467 – 1 April 1548) was King of Poland and Grand Duke of Lithuania from 1506 until his death in 1548. Sigismund I was a member of the Jagiellonian dynasty, the son of Casimir IV and younger brother of Kings John I Albert and Alexander I Jagiellon. He was nicknamed "the Old" in later historiography to distinguish him from his son and successor, Sigismund II Augustus.

Sigismund was born in the town of Kozienice in 1467 as the fifth son of Casimir IV and his wife Elizabeth of Austria. He was one of thirteen children and was not expected to assume the throne after his father. Sigismund's eldest brother and rightful heir Vladislaus II instead became the King of Bohemia, Hungary and Croatia as the successor to George of Poděbrady in Bohemia and then to Matthias Corvinus in Hungary, thus temporarily uniting these kingdoms. When Casimir died, the Polish-Lithuanian realm was divided between the remaining two older sons, with John Albert being crowned King of Poland, and Alexander as Grand Duke of Lithuania. Alexander inherited Poland following John Albert's sudden death in 1501. Hence, Sigismund's reign only began when he succeeded Alexander to both titles in 1506 at the age of 39.

A capable monarch and a patron of arts, Sigismund established Polish rule over Ducal Prussia and annexed the Duchy of Mazovia with Warsaw, while retaining the nation's wealth and prominence in the region. He made sure that his nephew Albert, Duke of Prussia, and Albert's Protestant successors would pay feudal homage or tribute to Polish monarchs as a sign of political and diplomatic dependence. This was observed until the Treaty of Bromberg in 1657 when Prussia gained its sovereignty. Sigismund and his commander Jan Amor Tarnowski also defeated Moldavia at Obertyn in 1531, and Muscovy in 1535, thereby strengthening the country's eastern borders. His 42-year reign was further marked by decisive contributions to Polish architecture, cuisine, language, and customs, especially at the behest of his second wife, the Italian-born Bona Sforza. Italian styles and fashions dominated at the height of the Polish Renaissance and Polish Golden Age, which developed the Roman Catholic identity of Poland. He was commemorated on a contemporary 200-złoty banknote.

Sigismund was married twice, first to noblewoman Barbara Zápolya from Hungary and then to Bona Sforza, the daughter of Gian Galeazzo Sforza, Duke of Milan. Their only son and the last Jagiellon king, Sigismund Augustus, was co-crowned vivente rege in 1529 and formally assumed throne when Sigismund the Old died in 1548.