Former Owner
- Mauni, Bālaṃbhaṭa1
- Maurice Johnson1
- Maurice Kann1
- Maurilio Morazio1
- Maximilian Henry of Bavaria1
- Maxwell Sommerville1
- Mayer Sulzberger19
- Mayfair Rare Books and Manuscripts1
- Mazliah Finzi1
- Maḥmūd al-Ustādār, d. 1396 or 71
- Maḥmūd bin Nāṣir1
- Maḥmūd ibn al-Shaykh al-Fattāḥ1
- McCormick Theological Seminary1
- Medingen Abbey1
- Melchior Daniel Neubronner1
- Melk Abbey2
- Menaḥem Naḥum, ha-Leṿi, mi-ḳ.ḳ. Dribin1
- Menno Hertzberger1
- Mercantile Library Company1
- Merlemont family1