Former Owner
- Maurice Kann1
- Maurilio Morazio1
- Mayfair Rare Books and Manuscripts1
- Mazliah Finzi1
- Maḥmūd al-Ustādār, d. 1396 or 71
- McCormick Theological Seminary1
- Medingen Abbey1
- Menno Hertzberger1
- Mercantile Library Company1
- Merlemont family1
- Meschatin La Faye family1
- Michael Bernays1
- Michael Kantakouzenos Şeytanoğlu1
- Michael Wodhull1
- Michaeliskonvent1
- Michel Chasles1
- Michel Ferdinand d'Albert d'Ailly1
- Michel Guibé1
- Michel de Léon1
- Michele Amari1