- Niccolò, Lapo di1
- Nicomachean ethics (Aristotle)1
- Nile River1
- Ninth century1
- Niẓām al-Mulk, 1018-10921
- Nofrio, Jacopo di1
- Northern France1
- Nukhbat al-fikar fī muṣṭalaḥ ahl al-athar (Ibn Ḥajar al-ʻAsqalānī, Aḥmad ibn ʻAlī)1
- Numerical division of sacred works1
- Numerology1
- Oaths (Islamic law)1
- Octavia, Empress, consort of Nero, Emperor of Rome, approximately 42-621
- Oedipus (Greek mythological figure)1
- Oratory1
- Oria, Johannes d'1
- Orlandini, Stefano1
- Orthodox Eastern Church1
- Orto, Giovanni dall'1
- Paffiere, Arcangelo1
- Paffiere, Matteo1