- Omid Rafieian
- Omkar Thakoor
- Omogbolade Ajayi
- Omya Hustadmarmor
- Onesun Yoo
- Onno Boxma
- Onur Dulgeroglu
- Opeyemi Fadipe
- Oriana Calderon
- Osbert Bastani
- Oscar A. Herrera-Restrepo
- Oscar Aguilar
- Oscar Dowson
- Oscar Repping
- Oskar Marko
- Osman Oguz
- Osman Rauf Karaaslan
- Osman Y. Ozaltin
- Osvaldo F. Morera
- Otilia Obodaru
