- O'Connell, Hayden1
- O'Grady, Joshua P.1
- O'Neill, Nathan1
- O'Sullivan, Thomas1
- O'connor, Shannon R.1
- O'mullan, Patrick J.1
- Obermaier, James1
- Olexa, Brendan D.1
- Onyema, Daniel1
- Ornstein, Graham1
- Orszulak, Adrian R.1
- Ott, Samuel1
- Owuor, Hezekiah K.1
- Ozcilingir, Eren1