Frederick William von Hessenstein

Frederick William, Prince von Hessenstein (17 March 1735, Stockholm — 27 July 1808, Panker), was a Swedish statesman and a soldier of German ancestry.

He was the eldest extramarital son of King Frederick I of Sweden, member of the House of Hesse, and his royal mistress Hedvig Ulrika Taube.

[3] Hessenstein was made a count of the Holy Roman Empire (in which his father's German realm, the landgraviate of Hesse-Kassel, was located) on 28 February 1741, and created a Swedish count on 29 March of the following year.

According to unverified rumors, he might have been the father of an extramarital daughter by Princess Sofia Albertina, Gustav III's sister.

Named Sophia, she was allegedly born in 1786, a year before the princess was sent to Germany as Abbess of Quedlinburg.