- Oria, Johannes d'1
- Orphans1
- Orphans in literature1
- Ospedale degli Innocenti (Florence, Italy)1
- Otto I, Holy Roman Emperor, 912-9731
- Oviedo family1
- Oviedo, Francisco de, 1728-1
- Oviedo, Gregorio de, 1721-17961
- Oviedo, Nicolás de, 1725-1
- Pablo de Santa Maria, Bishop of Burgos, approximately 1351-14351
- Pacheco de Silva, Juana1
- Pachisi1
- Paganelli, Roberto1
- Painted leather bindings1
- Painting1
- Painting, Japanese1
- Painting, Japanese--Edo period1
- Pakistan1
- Pakistan--Lahore1
- Pakistan--Wazīrābād1