Former Owner
- Madeleine Cosman1
- Mahdī ibn Muṣṭafá al-Ḥusaynī1
- Malachia Ormanian1
- Manuel Fernández del Castillo1
- Manūchihr Nukhastīn Āṣaf Qājār1
- Marie Cleophe de Sollario1
- Marie de Albano1
- Marienstiftsgymnasium1
- Markus Fugger1
- Mary Augusta Strachey1
- Matthaeus Lupin1
- Maximilian Henry of Bavaria1
- Mazliah Finzi1
- Maḥmūd bin Nāṣir1
- Maḥmūd ibn al-Shaykh al-Fattāḥ1
- Melchior Daniel Neubronner1
- Mobed Framji Fardunji Madan1
- Mobed Hormazdyar Mobed Khodabaksh1
- Mohammed bin Hamed bu Osman1
- Monastery at San Gregorio al Celio1