May 12 (Eastern Orthodox liturgics)

• Saint Domitilla the martyr (c. 81-96)[1][2]
• Saints Nereus and Achilleus the martyrs (100)[2][3]
• Saint Dracontius, Bishop of Nicaea (c. 1st to 3rd centuries)[4][note 2]
• Saint Epiphanius, Bishop of Salamis and Metropolitan of Cyprus (403)[2][5]
• Saint Calliope (Callitropos), nun, sister of St. Epiphanius of Cyprus.[6]
• Saint Sabinus, Archbishop of Cyprus (successor of St. Epiphanius to the Cypriot cathedra) (5th century)[7][8]
• Saint Polybius, Bishop of Cyprus, Wonderworker (5th century)[7][9]
• Saint Theophanes, Archbishop of Cyprus (7th century)[10][11][note 3]
• Patriarch Germanus I of Constantinople (740)[2][12]
• Venerable Theodore of Kythera, ascetic (922)[13][14]

• Saint Philip of Agira the Hieromartyr (103)[2][15][note 4]
• Martyr Pancratius of Rome (304)[2][16][17]
• Martyr Dionysius (Denis), uncle of St. Pancratius (304)[2][18]
• Saint Díoma, teacher of St Declan of Ardmore, patron-saint of Kildimo in Co. Limerick in Ireland (5th century)[18]
• Saint Modoald, Archbishop of Trier, related by blood and united by friendship with most of the saints of the Merovingian period (640)[2][18]
• Saint Rictrudis, Abbess of Marchiennes Abbey in Flanders (688)[18][note 5]
• Saint Æthelhard, Archbishop of Canterbury (805)[18]

• Saint Euthemius (Euthymius), Patriarch of Jerusalem (c. 1084? c. 1224?)[19])[20][note 6]
• Saint Nikitas the Sinaite[21]
• New Martyr John of Serres (15th century)[7][22]
• Saint Theophanes, Bishop of Solea (Solia), Cyprus, later a hermit in the Troodos Mountains; the Outpourer of Myrrh (1550)[23][note 7]
• Monk Dorotheus, (disciple of St. Dionysius of Troitse-Sergiyeva Lavra) (1622)[7][note 8]
• Venerable Dionysius of Radonezh, Archimandrite of the Troitse-Sergiyeva Lavra(1633)[7][26][27]
• New Martyr John of Wallachia, at Constantinople (1662)[7][28][29][note 9]
• Saint Anthony (Medvedev) of Radonezh, Archimandrite of Troitse-Sergiyeva Lavra (1877)[7][30]
• Repose of Saint Nectarius (Tikhonov) of Optina (1928)[31][note 10]
• Holy Elders of the Sofronievo-Molchensk (Molchansk) Hermitage (glorification in 2009):[32][33][note 11]

• Archimandrite Theodosy (Maslov);
• Hieromonk Serapion;
• Monk Sophronius (Batovrin);
• Novice Sergius (Tikhonov), fool-for-Christ.

• Consecration of the Cathedral of the Theotokos at Kiev (in 996)[37]
• Glorification (1913) of Hieromartyr Patriarch Hermogenes of Moscow (1612)[7][38][39]
• Discovery of the holy relics (1961) of Saint Irene of Lesvos the Virgin-martyr (1463)[40]
• Second Uncovering of the relics (1992) of Righteous Simeon of Verkhoturye (1642)[35]

• 
  Sts. Domitilla, Nereus, and Achilleus, by Peter Paul Rubens.
• 
  St. Epiphanius of Salamis.
• 
  Patriarch Germanus I of Constantinople.
• 
  Patriarch Germanus I of Constantinople and the Liddskaja icon.
• 
  St. Pancratius of Rome.

• May 12/25. Orthodox Calendar (PRAVOSLAVIE.RU).
• May 25 / May 12. HOLY TRINITY RUSSIAN ORTHODOX CHURCH (A parish of the Patriarchate of Moscow)
• May 12. OCA - The Lives of the Saints.
• Complete List of Saints. Protection of the Mother of God Church (POMOG).
• May. Self-Ruled Antiochian Orthodox Christian Archdiocese of North America.
• Dr. Alexander Roman. May. Calendar of Ukrainian Orthodox Saints (Ukrainian Orthodoxy - Українське Православ'я).
• May 12. Latin Saints of the Orthodox Patriarchate of Rome.
• May 12. The Roman Martyrology.

Greek Sources

• Great Synaxaristes: (in Greek) 12 ΜΑΪΟΥ. ΜΕΓΑΣ ΣΥΝΑΞΑΡΙΣΤΗΣ.
• (in Greek) Συναξαριστής. 12 Μαΐου. ECCLESIA.GR. (H ΕΚΚΛΗΣΙΑ ΤΗΣ ΕΛΛΑΔΟΣ).

Russian Sources

• (in Russian) 25 мая (12 мая). Православная Энциклопедия под редакцией Патриарха Московского и всея Руси Кирилла (электронная версия). (Orthodox Encyclopedia - Pravenc.ru).
• (in Russian) 12 мая (ст.ст.) 25 мая 2013 (нов. ст.). Русская Православная Церковь Отдел внешних церковных связей. (DECR).