April 27 (Eastern Orthodox liturgics)

• Saint Symeon the Kinsman of the Lord, Apostle of the Seventy and Hieromartyr (107)[1][2]
• Martyr Publius (Poplion), by the sword.[3][4]
• Martyr Lollion the Younger (Lollion the New).[4][5]
• Saint Pollion the Reader (Pollio), of Cibalis in Pannonia, burnt alive under Diocletian (306)[1][4][6]
• Saint Eulogius the Hospitable of Constantinople (6th century)[1][4][7][8]
• Saint Nicon, abbot of the Monastery of St. Gerasimus (6th century)[1][4]
• Saint Simeon Stylites the Younger of Cilicia (597), and his brother George.[9]
• Saint John of Cathares, Abbot of Cathares Monastery at Constantinople (839)[1][10][note 2]

• Saint Liberalis of Treviso, priest from the area near Ancona in Italy who worked for the conversion of the Arians and suffered much at their hands (400)[12]
• Saint Theophilus, Bishop of Brescia (427)[11][12][13]
• Saint Maughold, Bishop of the Isle of Man (c. 488)[4]
• Saint Assicus (Ascicus, Tassach), first bishop of Elphin, Ireland, converted to Christianity by Saint Patrick (490)[12][14]
• Saint Tertullian, eighth Bishop of Bologna in Italy (490)[12][note 3]
• Saint Enoder (Cynidr, Kenedr, Quidic) (6th century)[12]
• Saint Winewald, Abbot of Beverley in England (c. 731)[12][note 4]
• Saint Floribert of Liège (746)[1][4][12]

• Saint Stephen, abbot of the Kiev Caves and Bishop of Vladimir in Volhynia (1094)[1][16][17]
• New Hieromartyr Seraphim, Bishop of Phanarion and Neokhorion (1601)[4]
• New Martyr Elias (Ardunis) of Mount Athos (1686)[4]
• Saint Basil (Kishkin), Hieroschemamonk of Glinsk and Ploshchansk hermitages (1831)[1]

• Incineration of the relics of Saint Sabbas, first Archbishop of Serbia, by Sinan Pasha (1595)[1][20]
• Apparition of Our Lady of Kazan in Aleksandrovka, Saint Petersburg Governorate (1826)[21][22]
• Glorification (1999) of New Hieromartyr Hilarion (Troitsky), Archbishop of Verey (1929)[1]

• 
  St. Symeon the Kinsman of the Lord.
• 
  Martyrdom of St. Simeon (Menologion of Basil II, 10th century).
• 
  St. Anthimus of Nicomedia, (Menologion of Basil II, 10th century).
• 
  St. Simeon Stylites the Younger.
• 
  St. Simeon Stylites.

• April 27/May 10. Orthodox Calendar (Pravoslavie.ru).
• May 10 / April 27. Holy Trinity Russian Orthodox Church (A parish of the Patriarchate of Moscow).
• April. Self-Ruled Antiochian Orthodox Christian Archdiocese of North America.
• April 27. OCA - The Lives of the Saints.
• April 27. Latin Saints of the Orthodox Patriarchate of Rome.
• The Roman Martyrology. Transl. by the Archbishop of Baltimore. Last Edition, According to the Copy Printed at Rome in 1914. Revised Edition, with the Imprimatur of His Eminence Cardinal Gibbons. Baltimore: John Murphy Company, 1916. p. 118.
• Rev. Richard Stanton. A Menology of England and Wales, or, Brief Memorials of the Ancient British and English Saints Arranged According to the Calendar, Together with the Martyrs of the 16th and 17th Centuries. London: Burns & Oates, 1892. p. 184.

Greek Sources

• Great Synaxaristes: (in Greek) 27 Απριλίου. Μέγας Συναξαριστής.
• (in Greek) Συναξαριστής. 27 Απριλίου. Ecclesia.gr. (H Εκκλησία της Ελλάδος).

Russian Sources

• (in Russian) 10 мая (27 апреля). Православная Энциклопедия под редакцией Патриарха Московского и всея Руси Кирилла (электронная версия). (Orthodox Encyclopedia - Pravenc.ru).
• (in Russian) 27 апреля (ст.ст.) 10 мая 2013 (нов. ст.) Archived 2013-12-25 at the Wayback Machine. Русская Православная Церковь Отдел внешних церковных связей. (DECR).