| Otto Globocnik | Odilo Globocnik |
| Otto Hahn | Otto Hahn |
| Otto Heinrich Warburg | Otto Heinrich Warburg |
| Otto I Piękny | Otto of Greece |
| Otto II z Montferratu | Otto II of Montferrat |
| Otto Jespersen | Otto Jespersen |
| Otto Klemperer | Otto Klemperer |
| Otto Kotzebue | Otto von Kotzebue |
| Otto Kuusinen | Otto Ville Kuusinen |
| Otto Lilienthal | Otto Lilienthal |
| Otto Meyerhof | Otto Fritz Meyerhof |
| Otto Mueller | Otto Mueller |
| Otto Nerz | Otto Nerz |
| Otto Preminger | Otto Preminger |
| Otto Pérez Molina | Otto Pérez Molina |
| Otto Rank | Otto Rank |
| Otto Rehhagel | Otto Rehhagel |
| Otto Skorzeny | Otto Skorzeny |
| Otto Stern | Otto Stern |
| Otto Strandman | Otto Strandman |
| Otto Szmidt | Otto Schmidt |
| Otto Thierack | Otto Georg Thierack |
| Otto von Bismarck | Otto von Bismarck |
| Otto von Guericke | Otto von Guericke |
| Otto von Habsburg | Otto von Habsburg |
| Otto von Wächter | Otto Wächter |
| Otto Wagner | Otto Wagner |
| Otto Wallach | Otto Wallach |
| Otto Weininger | Otto Weininger |
| Otto Witte | Otto Witte |
| Otto Wittelsbach | Otto of Greece |
| Otto z Bambergu | Otto of Bamberg |
| Ottobeuren | Ottobeuren |
| Ottobrunn | Ottobrunn |
| Otton I | Otto I |
| Otton I Wielki | Otto I |
| Otton I Wittelsbach | Otto of Greece |
| Otton Orseolo | Otto Orseolo |
| Ottone Visconti | Ottone Visconti |
| Ottorino Respighi | Ottorino Respighi |
| Ottrau | Ottrau |
| Ottón Solís | Ottón Solís |
| otucha | comfort |
| otwarcie | open |
| Otwarcie Barnesa | Barnes Opening |
| Otwarcie szachowe | Chess opening |
| Otwarta ramka odczytu | Open reading frame |
| otwarte morze | open sea |
| Otwarte oprogramowanie | Open source |
| Otwartopęcherzowe | Ostariophysi |
| otwarty | open |
| Otwarty standard | Open standard |
| Otwarty Uniwersytet Izraela | Open University of Israel |
| otwieracz | opener |
| otwieracz do butelek | bottle opener |
| otwieracz do konserw | can opener |
| otwieracz do puszek | can opener |
| Otwieraă | Open out |
| otwierać | open |
| Otwock | Otwock |
