- ✠ St. Macarius of Alexandria, Hermit
- ✠ Saint Magloire, Abbot of Dol in Brittany
- ✠ St. Malachy d’Armagh, Primate of Ireland
- ✠ St. Mammertus, Archbishop of Vienne
- ✠ Saint Marcella, Widow
- ✠ St. Marcellinus, Bishop of Embrun
- ✠ Sts. Marcellus, the Centurion and his children, Martyrs
- ✠ St. Marcellus I, Pope and martyr
- ✠ Sts. Marcus and Marcellianus, Martyrs
- ✠ St. Margaret Bourgeoys, Foundress of the Congregation of Notre-Dame
- ✠ St. Margaret d'Youville, Foundress of the Sisters of Charity, called Grey Nuns
- ✠ St. Margaret Mary, Visitandine Nun, Apostle of the Sacred Heart
- ✠ St. Margaret of Antioch, Virgin and Martyr
- ✠ St. Margaret of Cortona, Franciscan tertiary, penitent
- ✠ St. Margaret of Scotland, Queen
- ✠ St. Maria Goretti, Virgin and Martyr
- ✠ St. Mark Evangelist, Martyr
- ✠ Saint Martha, Virgin
- ✠ St. Martin de Porres, Dominican Coadjutor Brother
- ✠ Saint Martin I, Pope and Martyr
- ✠ St. Martin of Tours, Missionary Bishop
- ✠ Saint Martina, Virgin and Martyr
- ✠ Holy Martyrs of Japan
- ✠ Holy Martyrs of Sebaste
- ✠ Holy Martyrs of Uganda
- ✠ Bl. Mary Assunta, Franciscan Missionary
- ✠ St. Mary Euphrasia Pelletier, Foundress of the Congregation of Our Lady of Charity of the Good Shepherd of Angers
- ✠ St. Mary Magdalen, Penitent
- ✠ St. Mary Magdalene of Pazzi, Virgin, Carmelite
- ✠ St. Mary Micaela, Foundress of the Institute of the Blessed Sacrament
- ✠ St. Mary of Egypt, Penitent
- ✠ St. Mary of Oignies, Recluse
- ✠ St. Mary of the Incarnation, Widow, Ursuline nun
- ✠ Bl. Mary of the Incarnation, Carmelite
- ✠ St. Mary of the Snows
- ✠ Mary, Queen of the World
- ✠ Divine Maternity of Mary
- ✠ St. Mathilda, Empress
- ✠ Saint Matthew, Apostle and Evangelist
- ✠ Saint Matthias, Apostle and Martyr
- ✠ Saint Maturinus, or Mathurin de Larchant, Priest and Confessor
- ✠ St. Maurice and the Theban Legion, Soldiers and Martyrs
- ✠ Saint Maurilius, Bishop of Angers
- ✠ St. Maximilian Kolbe, Priest, confessor, Conventual Fransiscan Friar, apostle of the Immaculate Conception
- ✠ Bl. Maximin Giraud, Visionary of La Salette
- ✠ St. Maximin of Verdun, (or Mesmin), Abbot of Micy
- ✠ Saint Maximus, Bishop of Riez
- ✠ St. Mechtildis of Hackeborn, Abbess
- ✠ Saint Medard, Bishop of Noyon and Tournai
- ✠ Bl. Melanie Calvat, Seeress of La Salette, Virgin
- ✠ St. Mello of Cardiff, Archbishop of Rouen
- ✠ St. Michael, the Archangel, Protector of the People of God
- ✠ St. Michael de los Santos, Trinitarian Priest
- ✠ St. Michael Garicoits, Founder of the Priests of the Sacred Heart of Betharram
- ✠ Miraculous Medal, gift of the Blessed Virgin Mary
- ✠ Saint Monica, Widow, mother of St. Augustin
