Baldwin I (July 1172 – c. 1205), the first emperor of the Latin Empire of Constantinople, as Baldwin IX Count of Flanders and as Baldwin VI Count of Hainaut, is one of the most prominent leaders of the Fourth Crusade, which results in the capture of Constantinople, the conquest of the greater part of the Byzantine Empire (at this time called the "Empire of Romania" by westerners), and the foundation of the Latin Empire, also known as Romania (not to be confused with the modern state Romania).

He loses his final battle to Kaloyan, the emperor of Bulgaria, and spends his last days as his prisoner.