| Samo | | - | Slovene, Medieval Slavic | |
| Sans | | - | Medieval Spanish | |
| Sence | | - | Medieval Spanish | |
| Sens | | - | Medieval Spanish | |
| Slavitsa | | - | Medieval Slavic (Hypothetical) | |
| Slavomir | | - | Croatian, Serbian, Medieval Slavic | |
| Sobeslav | | - | Medieval Slavic | |
| Stace | | - | Medieval English | |
| Stanimir | | - | Bulgarian, Russian, Serbian, Medieval Slavic | |
| Stanislav | | stah-nee-SLAHF (Russian) | Czech, Slovak, Russian, Ukrainian, Bulgarian, Slovene, Serbian, Croatian, Medieval Slavic | |
| Stanislava | | stah-nee-SLAH-vah (Russian) | Czech, Slovak, Bulgarian, Serbian, Croatian, Slovene, Russian, Medieval Slavic | |
| Sture | | STOO-re (Swedish) | Swedish, Medieval Scandinavian | |
| Sunnifa | | - | Medieval Scandinavian | |
| Svetopolk | | - | Medieval Slavic (Hypothetical) | |
| Svetoslav | | - | Bulgarian, Medieval Slavic | |