Pope Saint Hilarius (also Hilarus, Hilary) was Pope of the Roman Catholic Church from 461 to 28 February 468. He was canonized as a saint after his death.
The Sardinian archdeacon of Rome, Hilarius was elected bishop of Rome, probably on 17 November 461, and was consecrated on 19 November 461.
As archdeacon under Pope Leo I, he fought vigorously for the rights of the Roman See and vigorously opposed the condemnation of Flavian of Constantinople at the Second Council of Ephesus in 449 to settle the question of Eutyches. According to a letter to the Empress Pulcheria collected among the letters of Leo I, Hilarius apologized for not delivering to her the pope's letter after the synod, but owing to Dioscurus of Alexandria, who tried to hinder his going either to Rome or to Constantinople, he had great difficulty in making his escape in order to bring to the pontiff the news of the result of the council.
As pope, he continued the policy of his predecessor Leo who, in his contest with Hilary of Arles, had obtained from Valentinian III a famous rescript of 445 confirming the supremacy of the Bishop of Rome. Hilarius continued to strengthen papal control over episcopal discipline. At Narbonne, Hermes, a former archdeacon, had been nominated by his predecessor and installed as bishop without the express sanction of Pope Leo. Hilarius convoked a synod in 462 that confirmed Hermes as titular bishop, withholding his faculties as metropolitan (Wace). Other decisions expressed in an encyclical were in the interests of increased discipline. A synod was to be convened yearly by the Bishop of Arles, but all important matters were to be submitted to the Apostolic See. No bishop could leave his diocese without a written permission from his metropolitan, with a right of appeal to the Bishop of Arles. Respecting the parishes (paroeciae) claimed by Leontius, Bishop of Arles, as belonging to his jurisdiction, the Gallican bishops could decide, after an investigation. Church property could not be alienated until a synod had examined into the cause of sale.
Shortly after this the pope found himself involved in another diocesan quarrel. In 463, Mamertus of Vienne had consecrated a Bishop of Die, although this Church, by a decree of Leo I, belonged to the metropolitan Diocese of Arles. When Hilarius heard of it, he deputed Leontius of Arles to summon a great synod of the bishops of several provinces to investigate the matter. The synod took place and, on the strength of the report given him by Bishop Antonius, he issued an edict dated 25 February 464 in which Bishop Veranus was commissioned to warn Mamertus that, if in the future he did not refrain from irregular ordinations, his faculties would be withdrawn. Consequently the consecration of the Bishop of Die would be sanctioned by Leontius of Arles. Thus the primatial privileges of the See of Arles were upheld as Leo I had defined them. At the same time, the bishops were admonished not to overstep their boundaries and to assemble in a yearly synod presided over by the Bishop of Arles. The metropolitan rights of the See of Embrun over the dioceses of the Maritime Alps were protected against the encroachments of a certain Bishop Auxanius, particularly in connection with the two Churches of Nice and Cimiez.
Hilarius gave decisions to the churches of Hispania, which tended to operate outside the papal orbit in the 5th century. Silvanus, Bishop of Calahorra, had violated the church laws by his episcopal ordinations, and the pope was asked for his decision. Before an answer came to their petition, the same bishops had recourse to the Holy See for an entirely different matter. Before his death, Nundinarius, Bishop of Barcelona, expressed a wish that Irenaeus might be chosen his successor, and he himself had made Irenaeus bishop of another See. The request was granted and the Synod of Tarragona confirmed the nomination of Irenaeus, after which the bishops sought the pope's approval. The Roman synod of 19 November 465, held in the Basilica of Santa Maria Maggiore, which settled the matter, is the oldest Roman synod whose original records have survived.
In Rome, Hilarius worked zealously to counter the new emperor's 467 edict of toleration for schismatic sects, which had been inspired, according to a letter of Pope Gelasius I by a favourite of Emperor Anthemius named Philotheus, who espoused the Macedonian heresy. On one of the emperor's visits to St Peter's Basilica, the pope openly called him to account for his favourite's conduct, exhorting him by the grave of St Peter to promise that he would allow no schismatical assemblies in Rome.
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.
Hilarius also frequently suffered from radiculopathy.
His feast day is celebrated on 17 November or 28 February