| Name | Group | Language of Origin | Languages of Use | Meaning/Translation or Related Words | US 2021 |
|---|
| Osvaldo | Oswald | Old High German | Spanish, Italian | Words: Ass / rule | |
| Oswald | Oswald | Old High German | German, French, English | Words: Ass / rule | |
| Oswaldo | Oswald | Old High German | Spanish, Italian | Words: Ass / rule | |
| Oswin | Oswin | Old English | German, English | Words: deity / friend | |
| Otávio | Octavius/Octavia | Latin | Portuguese | the eighth, born in the eighth month | |
| Otello | Otto/Ute | Old High German | Italian | Words: wealth | |
| Otfried | Ottfried | Old High German | German | Words: wealth / peace, protection, safety | |
| Otger | Edgar/Edgarda | Old English | German | Words: wealth / spear | |
| Othello | Otto/Ute | Old High German | English | Words: wealth | |
| Othmar | Ottmar | Old High German | German | Words: wealth / famous, well-known | |
| Othon | Otto/Ute | Old High German | French | Words: wealth | |
| Otis | Otis | English | English | | #646 |
| Otmar | Ottmar | Old High German | German | Words: wealth / famous, well-known | |
| Otso | Otso | Finnish | Finnish | bear | |
| Ottaviano | Octavius/Octavia | Latin | Italian | the eighth, born in the eighth month | |
| Ottavio | Octavius/Octavia | Latin | Italian | the eighth, born in the eighth month | |
| Ottfried | Ottfried | Old High German | German | Words: wealth / peace, protection, safety | |
| Ottmar | Ottmar | Old High German | German | Words: wealth / famous, well-known | |
| Otto | Otto/Ute | Old High German | German, Italian, French, English | Words: wealth | #335 |
| Ottokar | Ottokar | Old High German | German | Words: wealth / vigilant | |
| Ottone | Otto/Ute | Old High German | Italian | Words: wealth | |
| Ottorino | Otto/Ute | Old High German | Italian | Words: wealth | |
| Otwin | Otwin | Old High German | German | Words: wealth / friend | |
| Ousmane | Osman | Arabic | French | bustard fledgling | |
| Oussama | Usama | Arabic | French | the lion | |
| Ove | Uwe | Old Norse | Scandinavian | Words: point, edge | |
| Ovid | Ovid | Latin | English | | |
| Ovidio | Ovid | Latin | Italian | | |
| Owen | Eoghan | Celtic | English, Irish | Words: yew | |
| Owen | Owen | Welsh | English, Welsh | | #22 |
| Øystein | Øystein | Old Norse | Scandinavian | Words: luck, happiness / stone | |
| Øyvind | Eivind | Old Norse | Scandinavian | Words: luck, happiness / winner | |
| Ozan | Ozan | Turkish | Turkish | the bard | |
| Ozzy | Oswald | Old High German | English | Words: Ass / rule | #712 |
