| O?ulcan | - | Turkish Name | O?uzhan | - | Turkish Name |
| Oakes | - | English Name | Oakley | - | English Name |
| Oaklie | - | English Name | Oalik | - | Eskimo Name |
| Oaluq | - | Eskimo Name | Oanaq | - | Eskimo Name |
| Oanuk | - | Eskimo Name | Oarvik | - | Eskimo Name |
| Oasik | - | Eskimo Name | Oatuk | - | Eskimo Name |
| Oavik | - | Eskimo Name | Oazik | - | Eskimo Name |
| Oba | - | Egyptian Name | Obaal | - | Phoenician Name |
| Obadiah | - | Biblical Name | Obaid | - | Muslim Name |
| Obal | - | Biblical Name | Obalesh | - | Hindu Name |
| OBannon | - | English Name | Obasi | - | African Name |
| Obed | - | Biblical Name | 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 |
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