Derna (; Arabic: درنة Darnah) is a port city in eastern Libya. It has a population of 100,000–150,000. It was the seat of one of the wealthiest provinces in the Barbary States, and remains the capital of the Derna District, with a much smaller area. Derna has a unique environment among Libyan cities, as it lies between green mountains, the Mediterranean Sea, and the desert. The city is also home to people of mixed origins.
The city was also the location of the famous Battle of Derna (1805), the first victory achieved by the United States Military on foreign soil. Occurring during the First Barbary War, the battle was fought between a force of roughly 500 US Marines and Mediterranean mercenaries and 4,000 or 5,000 Barbary troops.
Parts of the city were taken over by Islamic State (IS) militants in October 2014.