| May 1 | Saint Philip and Saint James, Apostles |
| May 2 | Athanasius, Bishop of Alexandria, 373 |
| May 4 | Monnica, Mother of Augustine of Hippo, 387 |
| May 7 | Harriet Starr Cannon, Religious, 1896 |
| May 8 | Dame Julian of Norwich, c. 1417 |
| May 9 | Gregory of Nazianzus, Bishop of Constantinople, 389 |
| May 10 | Nicolaus Ludwig von Zinzendorf, Prophetic Witness, 1760 |
| May 13 | Frances Perkins, Public Servant and Prophetic Witness, 1965 |
| May 16 | Martyrs of Sudan |
| May 17 | William Hobart Hare, Bishop of Niobrara, and of South Dakota, 1909 |
| May 19 | Dunstan, Archbishop of Canterbury, 988 |
| May 20 | Alcuin, Deacon, and Abbot of Tours, 804 |
| May 21 | John Eliot, Missionary among the Algonquin, 1690 |
| May 23 | Nicolaus Copernicus, 1543, and Johannes Kepler, 1543, Astronomers |
| May 24 | Jackson Kemper, First Missionary Bishop in the United States,1870 |
| May 25 | Bede, the Venerable, Priest, and Monk of Jarrow, 735 |
| May 26 | Augustine, First Archbishop of Canterbury, 605 |
| May 27 | Bertha and Ethelbert, Queen and King of Kent, 616 |
| May 28 | John Calvin, Theologian, 1564 |
| May 30 | Jeanne d’Arc (Joan of Arc), Mystic and Soldier, 1431 |
| May 31 | The Visitation of the Blessed Virgin Mary |
