The Jagiellonian or Jagellonian dynasty, otherwise the Jagiellon dynasty, the House of Jagiellon, or simply the Jagiellons, was the name assumed by a cadet branch of the Lithuanian ducal dynasty of Gediminids upon reception by Jogaila, the Grand Duke of Lithuania, of baptism as Władysław in 1386, which paved the way to his ensuing marriage to the Queen Regnant Jadwiga of Poland, resulting in his ascension to the Crown of the Kingdom of Poland as Władysław II Jagiełło, and the effective promotion of his branch to a royal dynasty. The Jagiellons reigned in several European countries between the 14th and 16th centuries. Members of the dynasty were Kings of Poland (1386–1572), Grand Dukes of Lithuania, Kings of Hungary, and Kings of Bohemia and imperial electors (1471–1526).

The Polish Golden Age was the Renaissance period in Poland and the Grand Duchy of Lithuania, roughly corresponding to the period of rule of the King Władysław II Jagiełło (1386–1434) and Sigismund II Augustus, the last of the Jagiellonian Dynasty monarchs, until his death in 1572. Some historians argue that the Polish Golden Age continued into the mid-17th century, when the Polish–Lithuanian Commonwealth was ravaged by the Khmelnytsky Uprising (1648–57) and by the Swedish and Russian invasion. During its Golden Age, the Commonwealth became one of the largest kingdoms of Europe and at its peak stretched from modern-day Estonia in the north to Moldavia in the south and from Moscow in the east to Brandenburg in the west.