Former Owner
- Martin Schøyen1
- Martinus Nijhoff1
- Marvin-L. Colker1
- Mary Bloch1
- Mary Schell Collins1
- Mary W. T. Dickinson5
- Mary, Queen of Scots1
- Maurice Kann1
- Mayfair Rare Books and Manuscripts1
- Merlemont family1
- Meschatin La Faye family1
- Michel de Léon1
- Michele Cavaleri2
- Middle Hill Rare Books & Manuscripts AB (Stockholm, Sweden)1
- Mikhail Golitsyn1
- Milton Fischmann20
- Minerva Kaiser1
- Minnis, Katherine1
- Mirmellus Arnandi1
- Monsieur de Bel Air1