Alexius IV Angelus was a Byzantine prince born around 1182, the son of Isaac II Angelus. He became co-emperor with his father after they were restored to the throne in 1203, following the intervention of the Fourth Crusade. His reign was marked by political instability and financial difficulties. In 1204, during the Fourth Crusade, Constantinople was captured by Crusader forces, leading to the fall of the Byzantine Empire. Alexius IV was deposed and later executed in 1204, marking a significant turning point in Byzantine history and the Crusades.