Sixtus I -- so called in the Liberian Catalogue by Optatus (l. 2) and Augustine (Ep. liii.) but Xystus (Greek), Xistus, or Xestus, in Catal. Felic., Irenaeus (adv. Haer. iii. 3), Eusebius of Caesarea (H. E. iv. 4, 5, and Chron.), Epiphanius (Haer. 97, 6)-- is one of the early bishop of Rome or pope (about 115-125), is conjectured to have been a priest and a martyr.

All assign him an episcopate of about 10 years, and place him in the reign of Hadrian. Catal. Liber. dates his episcopate 117-126; Eusebius (H. E.) 119-128; his Chronicle 114-124. Lipsius (Chronol. der röm. Bischof.) gives 124-126 as the possible limits for his death. The Felician Catalogue and the Martyrologies represent him as a martyr, and he is commemorated among the apostles and martyrs, after Saint Linus, Pope Anacletus I, Pope Clement I, in the canon of the mass. Nevertheless as Pope Telesphorus being the first bishop of Rome designated a martyr by Irenaeus, the claim to the title of Sixtus and other early bishop of Rome, to the great majority of whom it has been since assigned, is doubtful.

This article uses text from A Dictionary of Christian Biography and Literature to the End of the Sixth Century A.D., with an Account of the Principal Sects and Heresies by Henry Wace

Preceded by:
Pope Alexander I
List of popes Succeeded by:
Pope Telesphorus