| Sigfrido | | seeg-FREE-do (Italian), seeg-FREE-dho (Spanish) | Italian, Spanish | |
| Silvana | | seel-VAH-nah | Italian | |
| Silvano | | seel-VAH-no | Italian | |
| Silvestra | | - | Italian, Slovene | |
| Silvestro | | seel-VE-stro | Italian | |
| Silvia | | SEEL-vyah (Italian), SEEL-byah (Spanish) | Italian, Spanish, Portuguese, Romanian, Slovak, English, German, Late Roman, Roman Mythology | |
| Silvio | | SEEL-vyo (Italian), SEEL-byo (Spanish) | Italian, Spanish, Portuguese, Croatian | |
| Simona | | - | Italian, Czech, Slovak, Romanian, Lithuanian, Slovene, Bulgarian, Macedonian | |
| Simone (2) | | see-MAW-ne | Italian | |
| Simonetta | | see-mo-NET-tah | Italian | |
| Sisto | | - | Italian | |
| Sofia | | zo-FEE-ah (German), so-FEE-ah (Italian), soo-FEE-ə (Portuguese), SO-fee-ah (Finnish) | Norwegian, Swedish, German, Italian, Portuguese, Catalan, Greek, Finnish, Estonian, Slovak, Romanian | |
| Sonia | | SON-yə (English), SAWN-yə (English), SO-nyah (Italian) | English, Italian, Spanish, Portuguese, Romanian | |
| Stefania | | ste-FAH-nyah (Italian), ste-FAHN-yah (Polish) | Italian, Polish | |
| Stefano | | ste-FAH-no | Italian | |