The Massacre of the Latins was a large-scale massacre of the Roman Catholic (called "Latin") inhabitants of Constantinople, the capital of the Eastern Roman Empire, by the Eastern Orthodox population of the city in April 1182.

The predominance of the Italian merchants caused economic and social upheaval in Byzantium: it accelerated the decline of the independent native merchants in favour of big exporters, who became tied to the landed aristocracy, who in turn increasingly amassed large estates. Together with the perceived arrogance of the Italians, it fueled popular resentment amongst the middle and lower classes both in the countryside and in the cities.

The Roman Catholics of Constantinople at that time dominated the city's maritime trade and financial sector. Although precise numbers are unavailable, the bulk of the Latin community, estimated at 60,000 at the time by Eustathius of Thessalonica, was wiped out or forced to flee. The Genoese and Pisan communities especially were devastated, and some 4,000 survivors were sold as slaves to the (Turkish) Sultanate of Rum.

The massacre further worsened relations and increased enmity between the Western and Eastern Christian churches, and a sequence of hostilities between the two followed.