Former Owner
- Maurilio Morazio1
- Maximilian Henry of Bavaria1
- Maxwell Sommerville1
- Mayer Sulzberger4
- Mayfair Rare Books and Manuscripts1
- Mazliah Finzi1
- Maḥmūd bin Nāṣir1
- Maḥmūd ibn al-Shaykh al-Fattāḥ1
- Menaḥem Naḥum, ha-Leṿi, mi-ḳ.ḳ. Dribin1
- Menno Hertzberger1
- Mercantile Library Company1
- Merlemont family1
- Meschatin La Faye family1
- Messieurs Du Trieu2
- Michael Greenberg5
- Michael Kantakouzenos Şeytanoğlu1
- Michael M. Zagayski1
- Michael Tomkinson2
- Michael Wodhull1
- Michaeliskonvent1