- Marignis, Niccolò de1
- Maro, Guglielmo1
- Marriage (Roman law)1
- Martellini, Vincenzio1
- Martini, Giovanni1
- Martini, Girolamo1
- Martino, Barone di1
- Mary, Blessed Virgin, Saint, in the liturgy1
- Masjid al-Aqṣá (Jerusalem)1
- Masjid al-Nabawī al-Sharīf1
- Mass1
- Massachusetts1
- Massi, Francesca1
- Mathematics, Medieval1
- Mattei, Teo1
- Matteo, Bernardo di1
- Matteo, Giovanni di1
- Maurice, Saint, -approximately 2871
- Maximian, Emperor of Rome, approximately 240-3101
- Maḥbūbī, Maḥmūd ibn ʻUbayd Allāh, -1344 or 1345. Wiqāyat al-riwāyah fī masāʼil al-Hidāyah1