Gustavus Adolphus, also known in English as Gustav II Adolf or Gustav II Adolph, was King of Sweden from 1611 to 1632, and is credited with the rise of Sweden as a great European power. During his reign, Sweden became one of the primary military forces in Europe during the Thirty Years' War, helping to determine the political and religious balance of power in Europe. He was formally and posthumously given the name Gustavus Adolphus the Great by the Riksdag of the Estates in 1634.

The monarchy of Sweden is centred on the monarchical head of state of Sweden, by law a constitutional and hereditary monarchy with a parliamentary system. There have been kings in what now is the Kingdom of Sweden for more than a millennium. Originally an elective monarchy, it became a hereditary monarchy in the 16th century during the reign of Gustav Vasa, though virtually all monarchs before that belonged to a limited and small number of political families which are considered to be the royal dynasties of Sweden.