- Marie de Médicis, Queen, consort of Henry IV, King of France, 1573-16421
- Maritime law1
- Martellini, Vincenzio1
- Mary, Blessed Virgin, Saint1
- Materia medica1
- Medici, Alamanno de'1
- Medici, Bernardo d'Alamanno de'1
- Medici, Carlo de'1
- Medici, Francesca de'1
- Medici, Niccolò de'1
- Medici, Ottavia Altoviti1
- Medici, Vincenzo de'1
- Medicine--Study and teaching1
- Metaphysics1
- Metaphysics (Aristotle)1
- Military campaigns1
- Monasticism and religious orders--Rules1
- Monte, Leonora Concini, marchesa di1
- Morocco1
- Naples (Kingdom)1