| Rumena | | - | Bulgarian, Macedonian | |
| Ruzha | | - | Bulgarian, Macedonian | |
| Samuil | | sah-moo-EEL (Russian) | Russian, Bulgarian | |
| Sashka | | - | Macedonian, Bulgarian | |
| Sasho | | - | Macedonian, Bulgarian | |
| Sava | | - | Serbian, Bulgarian | |
| Sergei | | syer-GYAY (Russian), seer-GYAY (Russian) | Russian, Bulgarian | |
| Sergej | | syer-GYAY (Russian), seer-GYAY (Russian) | Russian, Bulgarian | |
| Sergey | | syer-GYAY (Russian), seer-GYAY (Russian) | Russian, Bulgarian | |
| Silva | | - | Bulgarian, Slovene | |
| Silviya | | - | Bulgarian | |
| Simeon | | SIM-ee-ən (English) | Biblical, Bulgarian, Serbian | |
| Simona | | - | Italian, Czech, Slovak, Romanian, Lithuanian, Slovene, Bulgarian, Macedonian | |
| Snezhana | | - | Russian, Bulgarian, Macedonian | |
| Sofiya | | sah-FEE-yah (Russian) | Russian, Ukrainian, Bulgarian | |