Former Owner
- Mariota Lyle1
- Martinus Nijhoff1
- Mary Schell Collins1
- Mary, Queen of Scots1
- Matthias Corvinus1
- Maurice Kann1
- Maxwell Sommerville1
- Merlemont family1
- Michael Tomkinson1
- Michel Chasles1
- Middle Hill Rare Books & Manuscripts AB (Stockholm, Sweden)1
- Minnis, Katherine1
- Monsieur de Bel Air1
- Morot1
- Morton Davis Mitchell1
- Mrs. F. W. Bartlett1
- Muriel Agnes Fry1
- Museo Cavaleri1
- Nicholas Chevalier1
- Nicolas Rauch1