Mark and Marcellian are martyrs venerated as saints by the Roman Catholic Church and the Eastern Orthodox Church. Their cult is sometimes associated with that of Saints Tranquillinus, Martia, Nicostratus, Zoe, Castulus, and Tiburtius, though not in the official liturgical books of the Church, which mention only Mark and Marcellianus among the saints for 18 June. Their mention in the General Roman Calendar on that date from before the time of the Tridentine calendar was removed in the 1969 revision, because nothing is known about them except their names, the fact of their martyrdom, and that they were buried on 18 June in the cemetery of Santa Balbina on the Via Ardeatina.
