Encyclopedias, Almanacs, Transcripts, and Maps
- Olmos, Andrés de
- Olomouc
- Olschwanger, Isaac Wolf
- Olshan, Isaac
- Olshausen, Justus°
- Olsson, Erik (Olai)
- Olsvanger, Immanuel
- Olyka
- Olympias, St.
- Omaha, Archdiocese of
- Oman, The Catholic Church in
- Omar Ibn al-Kha???b°
- Omar, Covenant of
- Omer (Ayin) Hillel
- Omer of Thérouanne, St.
- Omission
- Omnam Ken
- Omni Die Dic Mariae
- Omnibonus (Omnebene)
- Omri