Former Owner
- Mary W. T. Dickinson7
- Mary, Queen of Scots1
- Marymount College, Tarrytown4
- Mathias Schurer1
- Matteo Barresi1
- Matteo Luigi Canonici15
- Matthew Bloxam1
- Matthew Simpson Parkhurst1
- Matthias Corvinus1
- Maurice Johnson1
- Maurice Kann1
- Maxwell Sommerville1
- Mayer Sulzberger1
- Mazliah Finzi1
- Medingen Abbey1
- Mercantile Library Company1
- Messieurs Du Trieu2
- Michael Greenberg2
- Michael Tomkinson1
- Michael Wodhull1