| Frederick Augustus I | |
| Full Name: | German: Friedrich August |
| Duke of Oldenburg | |
| Succession: | Duke of Oldenburg |
| Predecessor: | Kings of Denmark as counts |
| Successor: | William I |
| Reign: | 1774–1785 |
| Spouse: | Princess Ulrike Friederike Wilhelmine of Hesse-Kassel |
| Issue: | Wilhelm, Duke of Oldenburg Princess Luise Hedvig Elisabeth Charlotte, Queen of Sweden and Norway |
| Royal House: | Holstein-Gottorp |
| Father: | Christian August of Holstein-Gottorp, Prince of Eutin |
| Mother: | Margravine Albertina Frederica of Baden-Durlach |
| Birth Date: | 20 September 1711 |
| Birth Place: | Gottorp, Schleswig |
| Death Place: | Oldenburg |
Friedrich August, Duke of Holstein-Oldenburg (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. He was born in Gottorp, Schleswig
Frederick Augustus married on 21 November 1752 to Princess Ulrike Friederike Wilhelmine of Hesse-Kassel; the couple had three children:
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.
He died in Oldenburg. His son and heir apparent, Peter Friedrich Wilhelm, succeeded him as Wilhelm I, Duke of Oldenburg.
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