| Name | Meaning | Gender | Origin |
|---|
| Olwen | White footprint | Female | Welsh |
| Opal | Jewel, gem | Female | Sanskrit |
| Oreo | American cookie brand consisting of two chocolate wafers with white cream filling. | Unisex | English |
| Oscar | Divine spear | Male | English |
| Otto | Wealth | Male | German |
| Owen | Well born, yew born | Male | Gaelic |
| Owena | Well born, yew born | Female | Gaelic |
| Pandora | All gift | Female | Greek |
| Peanut | Edible nuts eaten raw or roasted. | Unisex | English |
| Penn | Hill | Male | English |
| Penny | Weaver | Female | Greek |
| Pepper | Pepper | Female | English |
| Phoebe | Bright | Female | Greek |
| Pip | Lover of horses | Unisex | Greek |
| Pipsqueak | | Unisex | Hebrew |
| Pixie | A fairy like creature. Playful and mischievous | Female | English |
| Poco | Little. | Unisex | English |
| Pookie | | Unisex | Hebrew |
| Porkchop | | Unisex | Hebrew |
| Porky | | Unisex | Hebrew |
| Porsche | Pig | Unisex | Latin |
| Powell | Son of Hywel | Male | Welsh |
| Princess | Royal son | Female | English |
| Puddles | | Unisex | Hebrew |
| Pumpkin | Large round fruit with orange skin | Unisex | English |
| Quick | Speedy and fast. | Unisex | English |
| Rascal | One that is playfully mischievous | Unisex | English |
| Reese | Enthusiasm | Male | Welsh |
| Regan | Regal | Male | Gaelic |
| Ren | Water lily | Female | Japanese |