Participants
| Roman Ondráček | Czech Republic |
| Patrick Onen | Uganda |
| Tolu Oni | |
| Yvonne Onmonya | Nigeria |
| Justina Adwoa Onumah | Ghana |
| Larr Onyango | South Africa |
| Antoinette Oosthuizen | South Africa |
| Francois Oosthuizen | South Africa |
| Jess Oosthuizen | |
| Kathleen Oosthuizen | South Africa |
| Rowland Opisa | |
| Calvince Orage. | |
| Esther Orozco | Mexico |
| Rodomiro Ortiz | Peru |
| Estefania Ortiz Calva | United States of America |
| Bosco Oryema | |
| Osunde Osaigbovo Massy | |
| Kevin Osala | |
| Prince Osei | Ghana |
| Osarenkhoe Osemwegie | |
| Moses Osiru | |
| Elfadil Osman | Sudan |
| Hossam Eldin Osman | Egypt |
| Behailu Osro | Ethiopia |
| Silvia Otero | South Africa |
| Peggy Efua Oti-Boateng | Ghana |
| Maureen Otieno | Kenya |