| Name | Meaning | Gender | Origin |
|---|
| Nikko | Greek, people of victory | Male | English |
| Niles | son of Neil | Male | Scandinavian |
| Ninja | | Male | |
| Nipper | A small boy | Unisex | |
| Nitro | Short for Nitroglycerin a highly explosive liquid. | Male | |
| Noisy | | Male | Hebrew |
| Norton | From the north farm
| Male | English |
| Nutmeg | | Male | |
| Oakley | from the oak meadow | Male | English |
| 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 |
| Ollie | Latin, olive tree | Male | English |
| OMalley | | Male | Hebrew |
| Onyx | A gemstone with bands of different colours. | Male | |
| Opie | | Unisex | |
| Opus | | Male | Hebrew |
| Orca | | Unisex | |
| 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 | |
| Orion | Son of Fire
| Male | Greek |
| Orlando | Famous land
| Male | Italian |
| Oscar | God's spear.
| Male | English |
| Osiris | with strong eyesight | Male | Egyptian |
| Oswald | Divinely powerful
| Male | English |
| Othello | he has the sound of God | Male | Hebrew |
| Other | | Unisex | Hebrew |