SERGIUS I., pope from 687 to 701, came of an Antiochene family which had settled at Palermo, and owed his election as Conon’s successor to skilful intrigues against Paschalis and Theodorus, the other candidates. In the second year of his pontificate he baptized King Ceadwalla of Wessex at Rome. For rejecting certain canons of the Trullan (Quinisext) council of 692, Justinian II. commanded his arrest and transportation to Constantinople, but the militia of Ravenna and the Pentapolis forced the imperial protospatharius to abandon the attempt to carry out his orders. Sergius was followed by John VI. as pope.

SERGIUS II., pope from 844 to 847, a Roman of noble birth, elected by the clergy and people to succeed Gregory IV., was forthwith consecrated without waiting for the sanction of the emperor Lothair, who accordingly sent his son Louis with an army to punish the breach of faith. A pacific arrangement was ultimately made, and Louis was crowned king of Lombardy by Sergius. In this pontificate Rome was ravaged, and the churches of St Peter and St Paul robbed, by Saracens (August 846). Sergius was succeeded by Leo IV.

SERGIUS III. succeeded Pope Christopher in 904, and reigned till 911. His pontificate, so far as is known, was remarkable for nothing but the rise of the “pornocracy” of Theodora and her daughters. Sergius restored the Lateran palace, which had been shattered by an earthquake. After him Anastasius III. sat on the pontifical throne.

SERGIUS IV., pope from 1009 to 1012, originally bore the name of Peter, and is said to have been the first to change his name on accession to the pontificate. He was a mere tool in the hands of the feudal nobility of the city (see Rome) ; he was succeeded by Benedict VIII.