- O'Brien, Patrick Joseph1
- O'Dowd, Sean K.1
- O'Malley, Patrick D.1
- Ogi, Alyssa1
- Oglesby, Frank Edward1
- Okada, Haruna1
- Omura, David1
- Onario, Randy G.1
- Onderdonk, Jeffrey D.1
- Opperman, Gregory Lee1
- Orcutt, Zachary John1
- Oshetsky, Michael Ryan1
- Ossa, Daniel1
- Ostwald, Maggie A.2
- Oswald, Caleb Chase1
- Over, Robert A1