Former Owner
- Mario Maffei1
- Marion H. Gottfried1
- Marion Lawrence1
- Mark Lansburgh1
- Martin of Aragon1
- Marvin-L. Colker1
- Mary Augusta Strachey1
- Mary Bloch1
- Mary Elizabeth Holte1
- Mary Schell Collins1
- Mary, Queen of Scots1
- Matteo Barresi1
- Matthew Bloxam1
- Matthew Simpson Parkhurst1
- Matthias Corvinus1
- Maurice Johnson1
- Maurice Kann1
- Mayfair Rare Books and Manuscripts1
- Menno Hertzberger1
- Mercantile Library Company1