Friedrich August, Duke of Holstein-Oldenburg[citation needed] (20 September 1711 – 6 July 1785) was the son of Christian August, regent of Holstein-Gottorp and his wife Margravine Albertine Friederike of Baden-Durlach.

[citation needed] He was born in Gottorp, Schleswig[citation needed] Frederick Augustus married on 21 November 1752 to Princess Ulrike Friederike Wilhelmine of Hesse-Kassel; the couple had three children:[citation needed] Empress Catherine the Great of Russia, on behalf of her son Paul of Russia, last of the Dukes of Holstein-Gottorp, ceded the lands of that duchy to Denmark.

In exchange, Denmark ceded the Duchy of Oldenburg to the Prince Bishops of Lübeck, a cadet branch of the Dukes of Gottorp.

Thus, Friederich August of Holstein-Gottorp, Prince Bishop of Lübeck, became Duke of Oldenburg.

His son and heir apparent, Peter Friedrich Wilhelm, succeeded him as Wilhelm I, Duke of Oldenburg.