April 13 in Eastern Orthodox liturgical calendars is a feast day and a day of commemoration of saints and martyrs. Although some Orthodox churches use the Revised Julian Calendar and others use the traditional Julian calendar, the fixed commemorations for their respective April 13 are broadly the same, no matter which calendar is used.
Saints Theodosia the Princess (daughter of Emperor Hadrian), and the Eunuch Gerontios (c. 117-138)
Martyrs Dadas, Quinctillian and Maximus, the Lectors (c. 284-305) (see also: April 28, August 2)
Martyr Crescens of Myra in Lycia (3rd century) (see also: April 15 - Greek)
Hieromartyr Artemon, priest of Laodicea in Syria (303) (see also: March 24, April 12 - Greek)
Martyrs Eleutherius of Persia, and Zoilus, by beheading (4th century)
Martyr Theodosius, by the sword.
Martyr Thomais of Alexandria (476) (see also: April 14 - Greek)
Saint Martyrius, Patriarch of Jerusalem (486)
Saint Martin the Confessor, Pope of Rome (655) (see also: April 14 - Slavic)
Two Confessor Bishops, who were exiled to the Crimean peninsula together with St. Martin the Confessor, Pope of Rome (ca. 655) (compare also with: Bishops Sergiy, Pir and Theodor, April 14 - Romanian)
Venerable martyr Christophoros, of the Great Lavra of St. Sabbas the Sanctified.
Saint Ursus, Bishop of Ravenna and Confessor (396)
Saint Martius, Abbot, of Clermont in Gaul (c. 530)
Saint Hermenegild, son of the Visigothic King of Spain, Leovigild (586)
Saint Guinoch of Buchan (Guinoc, Guinochus), a Bishop in Scotland (ca. 838)
Saint Arsenios of Elassonna (Arsenius of Suzdal), Archbishop of Elassona (1625) (see also: April 29)
Venerable Herman, Archimandrite, of Svyatogorsk Monastery (1890)