Encyclopedias, Almanacs, Transcripts, and Maps
- Oscar Levant
- Oscar Niemeyer Soares Filho
- Osmond, Donny and Marie
- Osorina, Yulianya Ustinovna
- OSRD
- Ossip Joselyn Zadkine
- Ostorius Scapula
- Ostromir Gospel
- Ostrovsky, Alexander
- Osvaldo Aranha
- Oswald, Eleazer
- Oswald, Richard
- Oswaldo Lopez Arellano
- Oswiu
- Other American Colonies
- Other Military Operations and Peacekeeping Missions: U.S. Relations and Operations in Africa
- Other Military Operations and Peacekeeping Missions: U.S. Relations and Operations in Asia
- Other Military Operations and Peacekeeping Missions: U.S. Relations and Operations in Europe
- Other Military Operations and Peacekeeping Missions: U.S. Relations and Operations in the Caribbean and Central and South America
- Other Military Operations and Peacekeeping Missions: U.S. Relations and Operations in the Middle East