The House of Vasa or Wasa was a royal house that was founded in 1523 in Sweden. Its members ruled the Kingdom of Sweden from 1523 to 1654 and the Polish–Lithuanian Commonwealth from 1587 to 1668. Its agnatic line became extinct with the death of King John II Casimir Vasa in 1672.
The Vasa dynasty descended from a 14th-century Swedish noble family, tracing agnatic kinship to Nils Kettilsson (Vasa) (d. 1378), the fogde of Tre Kronor Castle in Stockholm. Several members held high offices during the 15th century. In 1523, after the Stockholm bloodbath and the abolition of the Kalmar Union, Gustav Eriksson (Vasa) became King Gustav I of Sweden and the royal house was founded. His reign is sometimes referred to as the beginning of the modern Swedish state, which included the King's break with the Catholic Church during the Protestant Reformation and the foundation of the Church of Sweden.