- O'Connor, Michael1
- O'Neil, Kara1
- O'sullivan, Finbarr1
- Ola, Emmanuel1
- Olaya, Grace1
- Oleynick, Robert1
- Olmsted, Dylan1
- Olson, Adam1
- Olson, Matthew1
- Onffroy, Maxwell2
- Onyema, Daniel1
- Osei, Michael1
- Oshiro-Leavitt, Clay N.1
- Ou, Baian1
- Ou, Jinjia1
- Ouellette, Cole1
- Owuor, Hezi1