Lastovo (pronounced [lâstɔv̞ɔ]; Italian: Lagosta, German: Augusta, Latin: Augusta Insula, Greek: Ladestanos, Illyrian: Ladest) is an island municipality in the Dubrovnik-Neretva County in Croatia. The municipality consists of 46 islands with a total population of 792 people, of which 93% are ethnic Croats, and a land area of approximately 53 km² (20 sq mi). The biggest island in the municipality is also named Lastovo, as is the largest town. The majority of the population lives on the 46 km² island of Lastovo.

Lastovo, like the rest of Roman province of Dalmatia, was settled by Illyrians. The Romans conquered and settled the entire area, retaining control until the Avar invasions and Slavic migrations in the 7th century. The Croats and other Slavic tribes subjugated by the Croats secured most of the Dalmatian seaboard. Sometime around the year 1000 the Venetians attacked and destroyed the settlement, due to the island's participation in piracy along the Adriatic coast. In the 13th century, Lastovo joined the Dubrovnik Republic where for several centuries it enjoyed a certain level of autonomy until the republic's conquest by the French, under Napoleon. Austria then ruled the island for the next century, then Italy and Yugoslavia until it finally became a part of the independent Republic of Croatia.