Anicetus was pope from circa 154 to 167. He was a Syrian from Emesa.

It was during his pontificate that Saint Polycarp, a disciple of Saint John the Divine, visited the Roman Church. Polycarp and Anicetus discussed on what date to celebrate Easter. Polycarp and his Church of Smyrna celebrated Easter on the 14th day of Nisan, which is the day of Pesach, while the Roman Church used to celebrate Easter on Sunday, since this is the weekday of Jesus' resurrection, and Jesus resurrection on a Sunday is the reason for Sunday being the holy day in Christianity. Polycarp and Anicetus did not agree on a common date, but Anicetus allowed Polycarp to keep the date he was used to. The controversy was to accelerate and grow more heated in the course of the following centuries.

The Christian historian Hegesippus also visited Rome during the pontificate of Anicetus. This visit is often referred to as sign for the early importance of the Roman See.

Anicetus was the first pope to condemn heresy by forbidding Montanism. He also actively opposed the Gnostics and Marcionism. According to Liber Pontificalis, Anicetus decreed that priests are not allowed to have long hair (perhaps because the Gnostics wore long hair.)

Anicetus is reported to have suffered martyrdom, but the dates vary between 16, 17, and 20 April, and no details on the kind of his martyrdom is known. His feast is on April 17.

Preceded by:
Pope Pius I
List of popes Succeeded by:
Pope Soter