Polycarp (/ˈpɒlikɑːrp/; Greek: Πολύκαρπος, Polýkarpos; Latin: Polycarpus; AD 69 – 155) was a Christian bishop of Smyrna.

[2] According to the Martyrdom of Polycarp, he died a martyr, bound and burned at the stake, then stabbed when the fire failed to consume his body.

In On Illustrious Men, Jerome similarly writes that Polycarp was a disciple of John the Apostle, who had ordained him as a bishop of Smyrna.

[10] Polycarp's epistle to the Philippians gives us some insights to the early usage of the New Testament from the quotes used within his letter.

Irenaeus reports that Polycarp was converted to Christianity by apostles, was consecrated a presbyter, and communicated with many who had seen Jesus.

Irenaeus states that on certain things the two speedily came to an understanding, while as to the observance of the New Covenant Passover, each adhered to his own custom, without breaking off full communion with the other.

[17] On his farewell, he said: "I bless you, Father, for judging me worthy of this hour, so that in the company of the martyrs I may share the cup of Christ.

However, a post-Eusebian addition to the Martyrdom of Polycarp, dates his death to Saturday, 23 February, in the proconsulship of Lucius Statius Quadratus, c. 155 or 156.

English patristic scholar William Cave (1637–1713) believed that this was evidence that the Smyrnaeans under Polycarp observed the seventh-day Sabbath, i.e. assembled on Saturdays.

B. Lightfoot records as a common interpretation of the expression "the Great Sabbath" to refer to Pesach or another Jewish festival.

According to Eusebius, Polycrates of Ephesus cited the example of Polycarp in defense of local practices during the quartodeciman controversy.

[24] Irenaeus, who as a young man had heard Polycarp preach, described him as[25] "a man who was of much greater weight, and a more steadfast witness of truth, than Valentinus, and Marcion, and the rest of the heretics.” Polycarp lived in an age after the deaths of the apostles, when a variety of interpretations of the sayings of Jesus were being preached.

His role was to authenticate orthodox teachings through his connection with the apostle John: "a high value was attached to the witness Polycarp could give as to the genuine tradition of old apostolic doctrine"[3] "his testimony condemning as offensive novelties the figments of the heretical teachers".

The Martyrdom of Polycarp is one of the earliest, if not the earliest, accounts of the veneration of the relics of a saint and the annual commemoration of a saint on the date of his or her death: And so we afterwards took up his bones which are more valuable than precious stones and finer than refined gold, and laid them in a suitable place; where the Lord will permit us to gather ourselves together, as we are able, in gladness and joy, and to celebrate the birth-day of his martyrdom for the commemoration of those that have already fought in the contest, and for the training and preparation of those that shall do so hereafter.

It was stolen on 14 March 2013 and never recovered; however, a fragment, taken from the arm on a previous occasion, was discovered and returned to the monastery on 14 July 2019.

[32] Polycarp in his letter calls Jesus the "son of God" and the "eternal high priest" and that "to him all heavenly and earthly things were subjected, whom every breath worships, who comes as a judge of the living and the dead".

He also highlighted the sinlessness of Jesus,[33] defended the doctrine of the Incarnation and the death of Christ on the cross, and clearly opposed docetism.