Former Owner
- Matthias Corvinus1
- Mauni, Bālaṃbhaṭa1
- Maurice Johnson1
- Maurice Kann1
- Maximilian Henry of Bavaria1
- Maxwell Sommerville1
- Mayer Sulzberger5
- Mayfair Rare Books and Manuscripts1
- Mazliah Finzi1
- Maḥmūd al-Ustādār, d. 1396 or 71
- Maḥmūd bin Nāṣir1
- Maḥmūd ibn al-Shaykh al-Fattāḥ1
- Melk Abbey2
- Menno Hertzberger1
- Mercantile Library Company1
- Merlemont family1
- Meschatin La Faye family1
- Messieurs Du Trieu2
- Michael Kantakouzenos Şeytanoğlu1
- Michael M. Zagayski1