Hilarius was a 5th-century bishop of Rome who served as pope from 461 until his death in 468. Born in Sardinia, he initially gained prominence as an archdeacon under Pope Leo I. During the Second Council of Ephesus in 449, he acted as a papal legate and famously challenged the condemnation of Flavian of Constantinople. Following his later ascension to the papacy, he focused heavily on reinforcing ecclesiastical authority and maintaining strict disciplinary standards across the western provinces, particularly in Gaul and Spain.