thumb|The [[Eastern Orthodox Church|Eastern Orthodox cross]]
Sep. 12 - Eastern Orthodox liturgical calendar - Sep. 14
All fixed commemorations below celebrated on September 26 by Orthodox Churches on the Old Calendar.
For September 13th, Orthodox Churches on the Old Calendar commemorate the Saints listed on August 31.
Feasts
- Forefeast of the Exaltation of the Cross.
Saints
- Hieromartyr Cornelius the Centurion (1st century)
- Saint Aristides the Athenian, martyr (120)
- Martyrs Serapion, Cronides, and Leontius, of Alexandria (c. 237) <small>(see also: September 11)</small>
- Martyr Straton of Nicomedia (3rd century)
- Martyr Seleucus of Galatia (320)
- Saint Eulogius I, Patriarch of Alexandria (608)|group=note
- Venerable Peter of Atroa, in Bithynia (or of Agrea) (early 9th century) <small>(see also: January 3)</small>
Pre-Schism Western saints
- , the father of St Eugenia of Rome, in whose home Sts Protus and Hyacinth were employed (3rd century)