| Name | Gender | Pronounced | Usage | Popularity |
|---|---|---|---|---|
| Olympos | - | Ancient Greek | ||
| Onesimos | - | Ancient Greek, Biblical Greek | ||
| Onesiphoros | - | Ancient Greek, Biblical Greek | ||
| Origenes | - | Ancient Greek | ||
| Pamphilos | - | Ancient Greek | ||
| Pancratius | - | Ancient Greek (Latinized) | ||
| Pankratios | - | Ancient Greek | ||
| Pantaleon | - | Ancient Greek | ||
| Panther | - | Ancient Greek | ||
| Pantheras | - | Ancient Greek | ||
| Paramonos | - | Ancient Greek | ||
| Pelagia | pe-LAHG-yah (Polish) | Ancient Greek, Greek, Polish | ||
| Pelagios | - | Ancient Greek | ||
| Pelagius | - | Ancient Greek (Latinized) | ||
| Pericles | PER-i-kleez (English) | Ancient Greek (Latinized) |