April 21 - Eastern Orthodox liturgical calendar - April 23
Holy Apostle Nathaniel of the Twelve (Bartholomew).
Venerable Theodore the Sykeote, Bishop of Anastasiopolis in Galatia.
Saint Vitalis of Gaza, monk of the monastery of Abba Seridus at Gaza.
Pope Saint Gaius.
April 16 - Eastern Orthodox liturgical calendar - April 18
April 22 (Eastern Orthodox liturgics)
…born in Dalmatia, became Pope of Rome, martyred with members of his family (296) (see also: August 11) Saint Agapitus I, Pope of Rome (536) (see also: April 17 - East) Saint Leo of Sens, Bishop of Sens in France for twenty-three years (541…
Hieromartyr Anicetus, Pope of Rome.
Hieromartyr Symeon (Shemon Bar Sabbae), Bishop in Persia.
Venerable Zosimas of Solovki.
St. Macarios (Notaras) of Corinth.