Former Owner
- Marsden J. Perry1
- Martin Picker1
- Mary Augusta Strachey1
- Mary Schell Collins1
- Mary Talbot, Countess of Shrewsbury1
- Mary W. T. Dickinson1
- Maurilio Morazio1
- Merlemont family1
- Michael Bernays1
- Miriam Lutcher Stark1
- Moritz Joseph Johann von Dietrichstein1
- Mortimer Frank1
- Mortimer Loeb Schiff1
- Mr. Hals1
- Museo Cavaleri1
- Nancy McGrath1
- Nettie Goldsmith Naumburg1
- Neustift Abbey1
- New York Academy of Medicine1
- Nicolas Antoine Labbey de Billy1