| Name | Gender | Pronounced | Usage | Popularity |
|---|---|---|---|---|
| Osanna | - | Italian (Rare) | ||
| Oscar | AHS-kər (English) | English, Irish, Portuguese (Brazilian), Italian, Swedish, Norwegian, Danish, Dutch, French, Irish My | ||
| Osvaldo | - | Spanish, Italian, Portuguese | ||
| Ottavia | - | Italian | ||
| Ottaviano | - | Italian | ||
| Ottavio | - | Italian | ||
| Ottone | - | Italian | ||
| Ottorino | - | Italian | ||
| Ovidio | - | Italian, Spanish | ||
| Palmira | - | Italian, Spanish, Portuguese | ||
| Palmiro | - | Italian | ||
| Pancrazio | pahn-KRAH-tsyo | Italian | ||
| Panfilo | - | Italian | ||
| Pantaleone | pahn-tah-le-ON-e | Italian | ||
| Paola | POW-lah (Italian), pah-O-lah (Spanish) | Italian, Spanish |