Polycrates of Ephesus

Polycrates of Ephesus (; ; fl. c. 130 – 196) was an Early Christian bishop at Ephesus. Polycrates convened a synod to establish Quartodecimanism as the official position on Easter for Asia. Composition of his letter has been dated to between AD 186 and 195.

The fragments of his letter to Pope Victor concerning Quartodecimanism provide a few details of his life. Polycrates came from a family at the center of the Christian community at Ephesus: he relates that seven of his relatives were bishops of the church in Ephesus, and he was the eighth. He also mentions that at the time he writes his letter to Victor, Polycrates had been "in the service of the Lord 65 years". Victor was inclined to excommunicate the churches of Asia, but a number of bishops advised him not to do this, including Irenaeus, pointing out that this was an ancient and unbroken tradition handed down to them from such important Christian figures as the apostles Philip and John. Victor eventually agreed to keep peace amongst the communities and not to excommunicate the churches of Asia.

Despite Polycrates convening a synod in Ephesus to declare Quartodecimanism official, this observance eventually died out. By the time of the First Council of Nicaea, Easter was agreed to be celebrated on a Sunday.