Former Owner
- Mary Bloch1
- Mary Elizabeth Holte1
- Mary Lacaita2
- Mary Lusher1
- Mary Schell Collins1
- Mary W. T. Dickinson10
- Mary, Queen of Scots1
- Matteo Barresi1
- Matteo Luigi Canonici16
- Matthew Bloxam1
- Matthew Donadski1
- Matthew Simpson Parkhurst1
- Matthias Corvinus1
- Maurice Johnson1
- Maurice Kann1
- Maximilian Henry of Bavaria1
- Mayfair Rare Books and Manuscripts1
- Melk Abbey2
- Menno Hertzberger1
- Mercantile Library Company1