Pope Hilarius was Pope from 19 November 461 to his death in 468.
Hilarius erected several churches and other buildings in Rome, for which the Liber Pontificalis, the main source for information about Hilarius, praises him. Two oratories in the baptistery of the Lateran, one in honour of St. John the Baptist, the other of St. John the Apostle, to whom he attributed his safe escape from the Council of Ephesus, are due to him, thus satisfying the question as to which Saints John the Lateran had been dedicated. He also erected a chapel of the Holy Cross in the baptistery, convents, two public baths, and libraries near the Basilica of St. Lawrence outside the Walls, in which church he was buried.
His feast day is celebrated on 17 November.