| Silvius | | - | Late Roman, Roman Mythology | |
| Simion | | - | Romanian | |
| Simon | | SIE-mən (English), see-MAWN (French), ZEE-mawn (German), SEE-mawn (Dutch) | English, French, Swedish, Norwegian, Danish, German, Dutch, Hungarian, Slovene, Romanian, Macedonian | |
| Simona | | - | Italian, Czech, Slovak, Romanian, Lithuanian, Slovene, Bulgarian, Macedonian | |
| Sixtus | | - | Late Roman | |
| 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 | |
| Sollemnia | | - | Late Roman | |
| Sonia | | SON-yə (English), SAWN-yə (English), SO-nyah (Italian) | English, Italian, Spanish, Portuguese, Romanian | |
| Sorin | | - | Romanian | |
| Sorina | | - | Romanian | |
| Sperantia | | - | Late Roman | |
| Spurius | | SPUWR-i-uws | Ancient Roman | |
| Stan (2) | | - | Romanian | |
| Stela | | - | Romanian | |
| Stelian | | - | Romanian | |