Leo III was the pope of the Catholic Church and leader of the Papal States from 795 until his death in 816. Born in Rome around 750, he served as a cardinal-priest under Adrian I before his own election. His pontificate was marked by a close alliance with the Frankish ruler Charlemagne, whom he famously crowned emperor in 800. Despite facing violent physical attacks and legal accusations from political rivals, Leo maintained his position through the protection of the Carolingian dynasty.