Encyclopedias, Almanacs, Transcripts, and Maps
- Orpaz Averbuch, Yitzhak
- Orphan (in the Early Church)
- Orphan, Orphanage
- Orsha
- Orshanski, Ilya (Elijah) Grigoryevich
- Orsi, Giuseppe Agostino
- Orsova
- Ort
- Orta, Garcia de
- Orten, Ji?í
- Ortenberg, Arthur (1926– ) and Claiborne, Liz
- Orthodox and Oriental Orthodox Churches
- Orthodox Church in America (OCA)
- Orthodox Church of Bulgaria
- Orthodox Church of Cyprus
- Orthodox Church of Georgia
- Orthodox Church of Greece
- Orthodox Church of Romania
- Orthodox Church of Russia
- Orthodox Church of Serbia