The Battle of Preveza was a naval engagement that took place on 28 September 1538 near Preveza in the Ionian Sea in northwestern Greece between an Ottoman fleet and that of a Holy League. The battle was an Ottoman victory which occurred in the same area in the Ionian Sea as the Battle of Actium in 31 BC. It was one of the three largest sea battles that took place in the sixteenth century Mediterranean, along with the Battle of Djerba and the Battle of Lepanto.

Preveza is a city in the region of Epirus, northwestern Greece, located on the northern peninsula of the mouth of the Ambracian Gulf. It is the capital of the regional unit of Preveza, which is the southern part of the region of Epirus. The Aktio-Preveza Immersed Tunnel –the first and so far only undersea tunnel in Greece– was completed in 2002. The 1,570 m long immersed tunnel connects Preveza in the north, to Aktio of western Acarnania to the south. The ruins of the ancient city of Nicopolis lie 7 kilometres north of Preveza.