Encyclopedias, Almanacs, Transcripts, and Maps
- Oaths, English Post-Reformation
- Obadiah, The Norman Proselyte
- Obadya, Abraham
- Obazine (Aubazine), Abbey of
- Obed
- Obed-Edom
- Obedas°
- Obediential Potency
- Obermann, Julian Joël
- Obermeyer, Jacob
- Obernai
- Obernik, Judah
- Oblate Sisters of Providence
- Oblate Sisters of St. Francis de Sales
- Oblate Sisters of the Most Holy Redeemer
- Oblates of Mary Immaculate
- Oblates of St. Charles
- Oblates of St. Francis de Sales
- Oblates of St. Joseph
- Obligation, Moral