| Name | Meaning | Gender | Origin |
|---|
| Oreo | American cookie brand consisting of two chocolate wafers with white cream filling. | Unisex | English |
| Oscar | Divine spear | Male | English |
| Oswald | Uncertain, possibly divine power | Male | German |
| Othello | Wealth | Male | German |
| Otis | One who hears well | Male | Greek |
| Oxford | From The Ox Ford | Male | English |
| Packard | One Who Packs | Male | English |
| Pal | A friend, buddy, chum. | Unisex | English |
| Pasha | Passover | Unisex | Greek |
| Patches | | Unisex | Hebrew |
| Paws | | Unisex | Hebrew |
| Peanut | Edible nuts eaten raw or roasted. | Unisex | English |
| Peekaboo | | Unisex | Hebrew |
| Pegasus | Myth Name (Winged Horse) | Unisex | English |
| Peppy | | Unisex | Hebrew |
| Percival | Pierce valley | Male | French |
| Percy | Pierce valley | Male | French |
| Pickles | Food flavored in a solution of vinegar | Unisex | English |
| Pico | | Unisex | Hebrew |
| Pinky | For Pinky Lee, the painting, and the color of her nose | Unisex | English |
| Pip | Lover of horses | Unisex | Greek |
| Pipsqueak | | Unisex | Hebrew |
| Pixel | | Unisex | Hebrew |
| Plato | Liberal | Male | Greek |
| Pluto | Wealth, riches | Unisex | Greek |
| Poco | Little. | Unisex | English |
| Pogo | | Unisex | Hebrew |
| Pookie | | Unisex | Hebrew |
| Prentice | Apprentice | Male | English |
| Primo | First | Male | Latin |