- Monastic and religious life1
- Montalvan, Alonso de1
- Montúfar, Alonso de, active 1512-15701
- Moriscos1
- Muñiz de Orellana, Francisco1
- Muñiz, Gonzalo1
- Nahuatl language1
- Navarre (Kingdom). Cortes1
- Naveda family1
- New Jersey--Princeton1
- New Spain. Viceroy1
- Odyssey (Homer)1
- Ontology1
- Order of the Golden Fleece1
- Ordinances, Municipal1
- Otto I, Holy Roman Emperor, 912-9731
- Ovando, Nicolás de, approximately 1460-15111
- Oviedo family1
- Oviedo, Francisco de, 1728-1
- Oviedo, Gregorio de, 1721-17961