April 21 (Eastern Orthodox liturgics)
April 20 - Eastern Orthodox liturgical calendar - April 22
All fixed commemorations below are observed on May 4 by Eastern Orthodox Churches on the Old Calendar.
For April 21, Orthodox Churches on the Old Calendar commemorate the Saints listed on April 8.
Saints
- Martyrs Theodore of Perge in Pamphylia, his mother Philippa, and Dioscorus, Socrates, and Dionysius Martyr Alexandra the Empress, wife of Diocletian, and those with her : Hieromartyrs Januarius, Bishop of Benevento, and his companions
- Saint Maximianus, Archbishop of Constantinople Venerable Anastasius Sinaita, Abbot of the Monastery of St. Catherine at Sinai
- Martyr Karol ''''
Pre-Schism Western saints
- Saint Cyprian, Bishop of Brescia
- Saint Beuno, Abbot, of Clynnog Fawr, Wales
- Saint Maelruba of Apur Crossan, Ireland
- Saint Frodulphus, a monk at St Martin's in Autun
Post-Schism Orthodox saints
- Saint Theodore the Philosopher of Kamske, martyred by Mongols
- Venerable Jacob, Abbot of Stromynsk Monastery, Radonezh
- Saint Alexis, Priest of, Bortsurmany, Nizhny Novgorod
New martyrs and confessors
- New Hieromartyr John Prigorovsky, Priest
- Saint Nicholas Pisarevsky, Confessor, Priest
- New Hieromartyr Alexis Protopopov, Priest
- New Hieromartyr Protopresbyter Basil Martysz of Teratyn, Chelm and Podlasie, Poland
Other commemorations
- Synaxis of The Mozdok Icon of the Mother of God
- Uncovering of the relics of St. Theodore, Abbot of Sanaxar Monastery
- Repose of Schemamonk Nicetas of Valaam Monastery
- Repose of Elder Dometian of Tula
- Repose of Hieroschemamonk Antipas II of Valaam Monastery
- Repose of Nun Stefanida of Kosovo, Serbia.