| Obed-edom | - | Biblical Name | Obet | - | Indonesian Name |
| Obi | - | African Name | Obiajulu | - | African Name |
| Obie | - | United States Name | Obike | - | American Name |
| Oboth | - | Biblical Name | Ociel | - | Latin Name |
| Ocran | - | Biblical Name | Octavian | - | Romanian Name |
| Octávio | - | Portuguese Name | Octha | - | Arthurian Name |
| Ocumwhowurst | - | American Name | Ocunnowhurst | - | American Name |
| Ocvran | - | Arthurian Name | Odair | - | Portuguese Name |
| Odakota | - | American Name | Odakuta | - | American Name |
| Odd | - | Norse Name | Oddleif | - | Norse Name |
| Oddur | - | Icelandic Name | Oded | - | Biblical Name |
| Odemar | - | Cyprien Name | Odern | - | Aborigin Name |
| Odero | - | African Name | Odil | - | French Name |
| Odin | - | United States Name | Odion | - | Egyptian Name |
| Odongo | - | African Name | Oealuk | - | Eskimo Name |
| Oevik | - | Eskimo Name | Oexik | - | Eskimo Name |
| Ofeig | - | Norse Name | Ófeigur | - | Icelandic Name |
| Oflaz | - | Turkish Name | Og | - | Biblical Name |
| Ogaleesha | - | American Name | Ogi | - | Indonesian Name |
| Ogilhinn | - | Scottish Name | Ogilvie | - | Scottish Name |
| Ogima | - | American Name | Oguz | - | Turkish Name |
| Oh-han | - | Korean Name | Oh-hyun | - | Korean Name |
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