Former Owner
- Mannheimer Hofbibliothek1
- Mannucci family1
- Manuel John Johnson1
- Marcantonio Contarini1
- Marchese Linterno1
- Marchese Porri-Carcani1
- Marcianus F. Rossi1
- Marie Cleophe de Sollario1
- Marie de Albano1
- Marie-Caroline of Bourbon-Two Sicilies, Duchess of Berry1
- Marie-François Duchesne de Beaumanoir1
- Marino Grimani1
- Mary Lacaita1
- Matthias Corvinus1
- Maurice Kann1
- Mayfair Rare Books and Manuscripts1
- Mercantile Library Company1
- Meschatin La Faye family1
- Michael Wodhull1
- Michiel family1