May 15 (Eastern Orthodox liturgics)

• The Seven Apostolic Men, Martyr Bishops, ordained in Rome by Saints Peter and Paul and sent to evangelize Spain (1st century):

• Saints Torquatus, Ctesiphon, Secundus, Indaletius, Caecilius, Hesychius, and Euphrasius[1][2][3]

• Saint Achillius (Achillios), Bishop of Larissa (330)[4][5]
• Saint Pachomius the Great, founder of cenobitic monasticism (348)[6][7]
• Saint Silvanus of Tabennisi, disciple of Saint Pachomius the Great (in the Thebaid) (4th century)[8]
• Saint Pyrrhus of Breti, one of Thirteen Assyrian Fathers (6th century)[9]
• Saint Barbarus the Myrrh-gusher of Greece (c. 820 - 829)[10]
• Saint Panegyrios of Cyprus (Panigerios, Panegyrius), Wonderworker of Malounta[11][12][note 2]

• Saint Liberator, bishop, martyr (130)[13]
• Saint Peter, Andrew, Paul, and Denise (150)
• Martyrs Cassius, Victorinus, Maximus, and their companions, in the Auvergne (Clermont) in France (c. 264)[2][3][note 3]
• Saint Eutychius of Ferento, bishop, martyr (270)[14]
• Martyr Simplicius of Olbia, Bishop, in Sardinia (c. 284-305)[2][3][15]
• Saint Sophia of Rome (303)
• Virgin recluse Caesarea of Otranto[3]
• Saint Reticius, bishop of Autun (4th century)[16]
• Saint Kaleb of Axum, king (542)
• Saint Severin of Sanseverino, Bishop of Settempeda (545)
• Saint Hilary of Galeata (Hilary of Tuscany), founder of the monastery called Galeata, later known as Sant'Ilaro (Sant'Ellero di Galeata) (558)[3][17]
• Saint Colmán of Oughaval (Colman mac Ua Laoighse, Colman Mc O'Laoighse), a disciple of St Columba and St Fintan of Clonenagh (6th century)[3][note 4]
• Virgin-martyr Dymphna of Geel, Flanders (c. 650)[2][3][18][19][20]
• Saint Gerebern (Gerebarn), presbyter, martyr (c.650)[21]
• Saint Waldalenus, founder of monastery of Bèze in France (7th century)[3]
• Saint Bercthun (Bertin), a disciple of St John of Beverley and first Abbot of Beverley in England (733)[3]
• Saint Bertha of Bingen (c. 757), and her son Saint Rupert of Bingen (732)[3]
• Saint Witesind of Córdoba, martyr (855)[22]
• Saint Hallvard Vebjørnsson of Husaby (1043)[23]

• Saint Anastasia of Latra[24]
• Saint Panigirius of Cyprus, Wonderworker[25]
• Saint Isaiah of Rostov, Bishop and Wonderworker (1090)[26]
• Saint Isaiah of the Kiev Caves, wonderworker (1115)[27][28]
• Saint Andrew the Hermit, of Mt. Kalana, Epirus, wonderworker (c. 1237 - 1271)[18][29]
• Saint Pachomius of Nerekhta, abbot (1384),[30][31] and Saint Silvanus of Nerekhta (1384)[32]
• Saint Cali of Anatolia (14th century)[33]
• Saint Euphrosynus of Pskov (Eleazar), abbot and wonderworker (1481)[34][35]
• Saint Serapion of Pskov, disciple of St Euphrosynus of Pskov (1481)[36][37][38][note 5]
• Saint Ignatius, Charalampius and Pamphilus, brothers and disciples of Euphrosynus of Pskov (15th century)[39]
• Saint Pachomius of Keno Lake Monastery (1525)[40][note 6]
• Saint Demetrius of Moscow the Wonderworker, Slain Crown Prince (1591)[43]
• Saint James of Putna, Metropolitan of Moldavia (1778)[44]
• Saint Elias (Chebotariov) of Verkhoturye, schemamonk (1900)[45]
• Saint Arethas (Katargin) of Valaam and Verkhoturye, archimandrite (1903)[18][32][46]

• Discovery of the revered icon of Kamoulianos "Acheiropoieta" ("made without human hands").[50][note 8]
• Icon of the Most Holy Theotokos Kazan-Vysha (1812)[51]
• Uncovering of the relics (1991) of Saint Arsenius of Konevits[52]
• Uncovering of the relics (2012) of Saint Elias (Ganzha) of Makeevka[53]
• Translation of the sacred relics of the Holy Apostle Titus of Crete, from Venice (which had taken the relics in 1669), back to the Greek Orthodox Archdiocese of Crete (1966)[54][55]
• Uncovering of the relics (1846) of Saint Tikhon, Bishop of Voronezh, wonderworker of Zadonsk (1783)[56][note 9]

• 
  Sts. Achillius of Larissa and Pachomius the Great.
• 
  St. Pachomius the Great.
• 
  Stained glass of St. Cassius of Clermont.
• 
  Chair of Saint Hilary of Galeata, in the cell in which the saint used to pray.
• 
  St. Bertha of Bingen.
• 
  St. Euphrosynus of Pskov.
• 
  St. Dmitry of Uglich.
• 
  St. Dmitry of Uglich.

• May. Self-Ruled Antiochian Orthodox Christian Archdiocese of North America.
• May 15/28. Orthodox Calendar (PRAVOSLAVIE.RU).
• May 28 / May 15. HOLY TRINITY RUSSIAN ORTHODOX CHURCH (A parish of the Patriarchate of Moscow).
• May 15. OCA - The Lives of the Saints.
• Complete List of Saints. Protection of the Mother of God Church (POMOG).
• May 15. Latin Saints of the Orthodox Patriarchate of Rome.
• May 15. The Roman Martyrology.

Greek Sources

• Great Synaxaristes: (in Greek) 15 ΜΑΪΟΥ . ΜΕΓΑΣ ΣΥΝΑΞΑΡΙΣΤΗΣ.
• (in Greek) Συναξαριστής. 15 Μαΐου. ECCLESIA.GR. (H ΕΚΚΛΗΣΙΑ ΤΗΣ ΕΛΛΑΔΟΣ).

Russian Sources

• (in Russian) 28 мая (15 мая). Православная Энциклопедия под редакцией Патриарха Московского и всея Руси Кирилла (электронная версия). (Orthodox Encyclopedia - Pravenc.ru).
• (in Russian) 15 мая (ст.ст.) 28 мая 2013 (нов. ст.). Русская Православная Церковь Отдел внешних церковных связей. (DECR).