Hedwig Eleonora of Holstein-Gottorp was Queen of Sweden from 1654 until 1660 as the wife of King Charles X Gustav. She served as regent during the minority of her son, King Charles XI, from 1660 until 1672, and during the minority of her grandson, King Charles XII, in 1697. She also represented Charles XII during his absence in the Great Northern War from 1700 until the regency of her granddaughter Ulrika Eleonora in 1713. Hedwig Eleonora was described as a dominant personality, and was regarded as the de facto first lady of the royal court for 61 years, from 1654 until her death.

Charles X Gustav, also Carl Gustav, was King of Sweden from 1654 until his death. He was the son of John Casimir, Count Palatine of Zweibrücken-Kleeburg and Catherine of Sweden. After his father's death he also succeeded him as Pfalzgraf. He was married to Hedwig Eleonora of Holstein-Gottorp, who bore his son and successor, Charles XI. Charles X Gustav was the second Wittelsbach king of Sweden after the childless king Christopher of Bavaria (1441–1448) and he was the first king of the Swedish Caroline era, which had its peak during the end of the reign of his son, Charles XI. He led Sweden during the Second Northern War, enlarging the Swedish Empire. By his predecessor Christina, he was considered de facto Duke of Eyland (Öland), before ascending to the Swedish throne. From 1655 to 1657, he was also Grand Duke of Lithuania.