Charles (Swedish: Karl) was a Swedish Prince, Duke and regent. He was born on 26 September 1748 in Stockholm, and died there 5 February 1818. Charles was Prince of Sweden and Duke of Södermanland. He was the son of King Adolphus Frederick and Queen Louisa Ulrika, née Princess of Prussia, a sister of Frederick the Great.
Charles was regent of Sweden 1792-1796 while his nephew, King Gustavus IV Adolphus, was under age. He was commonly referred to as "Duke Charles" or "the Duke-regent". After his nephew was declared adult, Duke Charles, lived privately and with little influence over Swedish government. He was interested in occultism.
Duke Charles married 7 July 1774 to Hedvig Elizabeth Charlotte of Holstein-Gottorp (1759-1818), a daughter of Charles's paternal uncle Duke Frederick August of Holstein-Gottorp and his wife, Duchess Ulrike Frederica Wilhelmina, née Princess of Hesse-Kassel. Charles and his wife had two children:
Louisa Hedvig (1797-1797)
Charles Adolphus (1798-1798)
Duke Charles was likely the father of Augusta von Fersen's son, Count Carl Axel Löwenhielm (1772-1861).