| Nickname | Real Name | City | Country |
| OAV | Alexey Orlov | Gus-hrustalnyy | Russia |
| Observer | Roman Makarov | St.Petersburg | Russia |
| Ocican | |||
| Octavio Campos Barroso | Octavio Campos Barroso | Spain | |
| Octavio Fernández Heredero | Octavio Fernandez Heredero | Madrid | Spain |
| Odintsoff | St.Petersburg | Russia | |
| Oldman | Dmitry Grigoryev | Moscow | Russia |
| Oleg Origin | Artem Orlov | St.Petersburg | Russia |
| Oliver West | Vassa // alias | ||
| Omega Software Graphics | Jan Palenícek | Šumice | Czech Republic |
| Ondřej Mihula | Ondrej Mihula | Czech Republic | |
| One Man | Aleksandr Kovalerov | Minsk | Belarus |
| Ooz | Adam Powroźnik | Poland | |
| Organism | Aleksej Novikov | Dzerzhinsk | Russia |
| Orion | Yekaterinburg | Russia | |
| Orlando Araujo Martin | Orlando Araujo Martin | ||
| Oscar | Sergej Sokolov | Izhevsk | Russia |
| Oscar | Novosibirsk | Russia | |
| Oscar Garcia | Oscar Garcia | Barcelona | Spain |
| Oscar Ramiro Cairols | Oscar Ramiro Cairols | València | Spain |
| Oscar Vives Martinez | Oscar Vives Martinez | Spain | |
| Ostrich Soft | Mariupol | Ukraine | |
| OWL | Oleg Smirnov | Rybinsk | Russia |
| Ozzyoss | Martin Daniel | Chotěboř | Czech Republic |
| Олег Копытов | Vassa // alias | ||
| Олег Москаленко | Oleg Moskalenko | Lviv | Ukraine |
| Олег Тихомиров | Oleg Tihomirov | ||
| Отец хлеба | moroz1999 // alias | ||
| Virtual TR-DOS Authorz Database / 28 of 1806 authorz |
28.02.2020 | ||