Hippolytus of Rome was a Christian theologian and writer active in the late second and early third centuries CE. He served as a presbyter in Rome and was a prominent figure in early theological debates. He was a fierce opponent of teachings he considered heretical, particularly Monarchianism, which emphasized the single personhood of God.

His career was marked by a major ecclesiastical conflict. Hippolytus was elected as a rival bishop, or antipope, in opposition to the bishops Callistus I, Urban I, and Pontian. This schism was rooted in doctrinal disputes and disagreements over church discipline. The conflict ended around 235 CE when both Hippolytus and Pope Pontian were exiled. Tradition holds that they reconciled before dying as martyrs.

Hippolytus was a prolific author, though many of his works are lost. His surviving writings include the Refutation of All Heresies, an important source on early Christian polemics and Gnostic thought. Another significant text is The Apostolic Tradition, a detailed church order describing early Roman Christian liturgy and rites; however, its exact authorship is debated by scholars. He also wrote the oldest surviving Christian commentary on a book of the Bible, his Commentary on Daniel.

He is a crucial figure for understanding the development of early Western Christian doctrine and practice. His works provide valuable evidence for third-century theology, liturgy, and church structure. His eventual reconciliation made him a later symbol of unity, and he is venerated as a saint in multiple Christian traditions.