| Oceana | Oiva | Olli | Orest | Oscar | Otfried | Ottokar |
| Ocke | Oivi | Ollie | Orhan | Ositha | Otfriede | Ottomar |
| Octavia | Okan | Olly | Orla | Oskar | Otger | Ottomax |
| Octavian | Oke | Olof | Orlando | Oskari | Otgund | Ottona |
| Octavius | Okka | Olofa | Ornella | Osman | Otgunde | Ottone |
| Oda | Okke | Olrik | Orschel | Osmar | Othenio | Ottorino |
| Odalberta | Okko | Oluf | Orsola | Osmo | Otil | Ottwine |
| Odalinde | Oktavia | Olympia | Orson | Osmund | Otis | Otwald |
| Odde | Oktavian | Olympus | Ortensia | Osmunde | Otkar | Otward |
| Oddo | Ola | Omar | Ortfried | Ossel | Otker | Otwin |
| Ode | Olaf | Omer | Ortger | Ossi | Otl | Otwine |
| Odette | Olaus | Omke | Orthia | Ossian | Otli | Owen |
| Odila | Olav | Omme | Orthild | Ossip | Otlinde | Oxana |
| Odile | Olavi | Ommo | Orthilde | Ossy | Otmar | Ozeana |
| Odilia | Oldrik | Ömür | Orthold | Ostara | Otmun | |
| Odilie | Oldwig | Ona | Ortlieb | Osterhild | Otmund | |
| Odilio | Ole | Onni | Ortlind | Osterlind | Otso | |
| Odilo | Oleg | Onno | Ortlinde | Ostian | Ott | |
| Odin | Olegard | Ontje | Ortolf | Oswald | Ottar | |
| Odina | Olf | Onur | Ortolt | Oswalda | Otte | |
| Odine | Olga | Oona | Ortraud | Oswalde | Ottegebe | |
| Odkar | Olievero | Opal | Ortrud | Oswin | Ottfried | |
| Odo | Olinde | Ophrah | Ortrun | Oswina | Otthein | |
| Odoardo | Oliva | Ophelia | Ortwald | Oswine | Ottheinrich | |
| Odomar | Olive | Oprah | Ortwin | Otberga | Ottheinz | |
| Ofelia | Oliver | Ora | Orville | Otbert | Otthermann | |
| Offe | Olivet | Orania | Orvo | Otberta | Otti | |
| Offo | Olivia | Oranna | Osane | Otburg | Ottilie | |
| Ohto | Olivier | Orell | Osbert | Otburga | Ottmar | |
| Oili | Olla | Orella | Osberta | Otburgis | Otto |