Former Owner
- Mary Augusta Strachey1
- Mary Elizabeth Holte1
- Mary Schell Collins1
- Mary Stanley, Countess of Derby1
- Mary Talbot, Countess of Shrewsbury1
- Mary, Queen of Scots1
- Mathias Schurer1
- Matteo Barresi1
- Matthew Bloxam1
- Matthew Hale1
- Matthew Simpson Parkhurst1
- Matthias Corvinus1
- Mauni, Bālaṃbhaṭa1
- Maurice Johnson1
- Maurice Kann1
- Mayfair Rare Books and Manuscripts1
- Mazliah Finzi1
- Menno Hertzberger1
- Mercantile Library Company1
- Merlemont family1