Pope Sergius IV, né Pietro Boccapecora (died May 12, 1012) was pope from July 31 1009 until his death. The date of his birth is unknown. The name of his birth is believed to have been Pietro (Peter) Martino Boccapecora, but he adopted the name Sergius upon accession to the pontificate. He is sometimes cited as the first Pope to adopt a new name, although Pope Agapetus I is another possibile originator of this tradition.

Pietro Boccapecora was the son of a shoemaker (also named Pietro) who lived in the city of Rome. Despite his family's poor background, he performed well after entering the church, and rose quickly through the ranks. In 1004, he became Bishop of Albano. Upon the abdication of Pope John XVIII in 1009, he was elected pope, and adopted the name Sergius IV.

The power held by Sergius IV was often overshadowed by Crescentius , the ruler of the city of Rome at the time. Some historians have claimed that Sergius IV was essentially a puppet ruler for Crescentius. Others, however, claimed that Sergius IV resisted Crescentius's power. There is some evidence that Sergius IV gave political backing to an anti-Crescentius faction in the city.

Acts sometimes attributed to Sergius IV include measures to relieve famine in the city of Rome, the exemption of certain monasteries from episcopal rule, and a papal bull calling for Islam to be driven from the Holy Land; this bull was actually invented during the later crusades, helping to justify the expedition against Jerusalem and the Church of the Holy Sepulchre, which had been destroyed in 1009 by the Fatimid caliph al-Hakim bi-Amr Allah, during Sergius' reign.

Sergius IV died on May 12, 1012, and was followed in the papacy by Benedict VIII. Sergius IV was buried in the Lateran Basilica, and is sometimes venerated as a saint by the Benedictines.