Sisinnius

Saint Sisinnius was a martyr of Cyzicus, regarded as bishop of that city, in the third and fourth centuries, venerated by all the Churches that accept the veneration of saints. The Byzantine synaxaria commemorate him on 23 November, but their various recensions give information so different that one doubts whether there is one man or saints of the same name. According to some recensions, Sisinnius was bishop of Cyzicus and cared for the Christians imprisoned for their faith; accused of being a Christian himself, he was arrested, subjected to various tortures and finally beheaded in the time of the emperor Diocletian. According to other recensions, Sisinnius lived in the Arian crisis at the beginning of the fourth century and took part in the council of Nicaea of 325; in this case he did not suffer martyrdom but died of old age.

A saint called Sisinnius, commemorated on 21 November, also appears in the Hieronymian Martyrology, together with others, but without any indication of place. Caesar Baronius introduced his veneration into the Roman Martyrology on 23 November, without mentioning an episcopate.