Former Owner
- Mannucci family1
- Manūchihr Nukhastīn Āṣaf Qājār1
- Mario Maffei1
- Mark Augspürger1
- Mark Lansburgh1
- Markus Fugger1
- Mary Augusta Strachey1
- Mary Schell Collins1
- Matthias Corvinus1
- Maurilio Morazio1
- Mazliah Finzi1
- Melk Abbey1
- Merlemont family1
- Michael Wodhull1
- Michel Chasles1
- Michel de Léon1
- Michele Amari1
- Moritz Dessauer1
- Moritz Joseph Johann von Dietrichstein1
- Murray Anthony Potter1