| Name | Meaning | Gender | Origin |
|---|
| Oboe | | Unisex | |
| Odie | Melody | Unisex | French |
| Ody | | Unisex | |
| Olaf | ancestor's relic | Male | Norse |
| Oliver | The olive tree. The biblical olive tree symbolizes fruitfulness and beauty and dignity. Extending an olive branch signifies an offer of peace.
| Male | Latin |
| Omar | first son, disciple; gifted speaker; famous | Male | Arabic |
| Oreo | American cookie brand consisting of two chocolate wafers with white cream filling. | Male | |
| Oreo | American cookie brand consisting of two chocolate wafers with white cream filling. | Male | |
| Oro | Gold
| Male | Spanish |
| Otis | Wealthy.
| Male | |
| Ozzie | Strong
| Male | Short |
| Pacorro | Free
| Male | |
| Paget | Attendant
| Male | |
| Palermo | | Male | Hebrew |
| Panther | A black leopard | Male | |
| Patches | | Male | |
| Patrick Delaney Podmore | The leader of the headless hunt.
| Male | |
| Patsy | From Patricia - Well born maiden | Male | English |
| Paulie | | Unisex | |
| Peanut And Butter | | Unisex | |
| Pebbles | after the character in 'The Flintstones' cartoons | Male | |
| Pegasus | | Male | |
| Pepper | A spice or condiment. | Male | Sanskrit |
| Peppy | | Male | |
| Percival | Hero of several Arthurian stories
| Male | |