Encyclopedias, Almanacs, Transcripts, and Maps
- OXFORD ENGLISH
- OXFORD ENGLISH DICTIONARY
- Oyak (Ordu Yardimlasma Kurumu)
- Oz ve Shalom (Netivot Shalom)
- Ozarks
- O’Connor, Donald David Dixon Ronald
- O’Hair, Madalyn Murray
- O’Neill, Thomas Philip, Jr. (“Tip”)
- P'u Noi
- Paar, Jack Harold
- Pachacamac
- Pachacuti (c. 1391–c. 1473)
- Pachamama
- Pacheco Areco, Jorge (1920–1998)
- Pacheco da Silva, Osvaldo (1918–)
- Pacheco, Gregorio (1823–1899)
- Pacheco, José Emilio (1939–)
- Pacheco, Maria Cristina (1941–)
- Pacheco, María Luisa (1919–1982)
- Pachuca