pope from 1009 to 1012. He became bishop of Albano, Papal States, about 1004. Elected to succeed Pope John XVIII, he was consecrated on July 31, 1009; he changed his name from Peter to Sergius out of deference to the first pope. He was powerless in the hands of the Roman nobles and the patrician Crescentius II, head of the Crescentii, an infamously powerful Roman family that manipulated the papacy from the mid-10th to the early 11th century.

While temporally weak, Sergius was particularly noted for his aid to the poor and for granting privileges to several monasteries. After his death there was speculation that he had been murdered. He was buried in the St. John Lateran Basilica, Rome.