- O'Connell, Piper1
- O'Connor, Delainey C.1
- O'Connor, Michael1
- O'Neil, Sarah Elizabeth1
- O'grady, Joshua1
- Oconnor, Sean1
- Oleynick, Robert1
- Oliner, Steven1
- Olmsted, Dylan1
- Orlandi, Giancarlo1
- Ornstein, Graham1
- Ou, Jinjia1
- Ouellette, Cole1
- Owuor, Hezekiah K.1