Prevlaka (pronounced [prɛ̂ʋlaka]) is a small peninsula in southern Croatia, near the border with Montenegro, at the entrance to the Bay of Kotor on the eastern Adriatic coast.

Because of its strategic location in the southern Adriatic, in the aftermath of the SFR Yugoslav breakup, the peninsula became subject to a territorial dispute between Croatia and FR Yugoslavia, a federal state that included Montenegro. The territory was functional under UN until 2002. The UN mission ended in December 2002 and the territory that had previously been part of SR Croatia was returned to the Republic of Croatia. An agreement was signed by both sides five days before the departure of the UNMOP that demilitarized Prevlaka, though implementation still has a temporary character.

The narrow, uninhabited peninsula is 2.6 kilometres (1.6 mi) long and only 150–500 metres (500–1,600 ft) wide, covering an area of 93.33 hectares (230.6 acres) (just under 1 square kilometre or 0.4 square miles).

The word prevlaka means 'portage'. Cape Oštro (Punta Oštro/Punta d'Ostro), located at the very tip of the peninsula, is the southernmost point of mainland in Croatia. Along with the small Montenegrin island of Mamula, which sits some 2 kilometres (1.2 mi) east of Cape Oštro, in addition to being two sides of an international maritime border, the two spots present observation entry points into the Bay of Kotor.

North of the Prevlaka isthmus, just within the Bay of Kotor, lie the two less prominent capes Konfin and Kobila, to the northwest of which is a road border crossing between Croatia and Montenegro. The D516 highway connects it to Konavle and the D8; northwards the road connects to Njivice, Sutorina, and Igalo.

Konavle and the Prevlaka peninsula was bought by the Republic of Ragusa from the Bosnian Kingdom in the early 15th century to protect its eastern flank. Ragusans fortified Cape Oštro in 1441. Cape Kobila was the boundary with Sutorina under the Ottoman Empire's control since 1699.

In 1806, during Napoleon's conquest of Europe, King Alexander I of Russia was intent on stopping French advances in the Adriatic and to that end deployed a Mediterranean expedition led by vice-admiral Dmitry Senyavin, that by September 1806 made considerable territorial gains in the area, including Prevlaka and the entire Bay of Kotor. In July 1807, the Russians and the French struck a deal in the first Treaty of Tilsit for the area to be handed over to the First French Empire. In 1808, the French assigned the newly acquired territory over to their client state called the Napoleonic Kingdom of Italy before in 1810 reassigning it back into the First French Empire proper as part of the Illyrian Provinces, their recently created autonomous subdivision.

Following Napoleon's defeat, former Ragusan territory including Prevlaka came under the rule of the Austrian Empire in 1813. Austrian rule was ratified by the Congress of Vienna in 1815, and the territory became part of its newly created internal administrative subdivision, the Kingdom of Dalmatia. It remained as such after the transformation of Austrian Empire into the dual monarchy of Austria-Hungary following the Congress of Berlin in 1867. Towards the end of the 19th century, on the suggestion of General Lazar Mamula, the Austro-Hungarian authorities decided to build a fort on Punta d'Ostro, along with another in the island of Mamula in order to ensure military control over the entrance into the Bay of Kotor. The Austrian authorities successfully fortified cape Mirište and the islet of Mamula. The authorities reportedly also decided to compensate local farmers for the expropriated land, but no money was paid until the collapse of the dual monarchy.