- Sidney
- Sidwell
- Siebenthal
- Siggery
- Sights
- Sigler
- Silby
- Siliezar
- Silk
- Sill
- Silliton
- Sills
- Silsby
- Silvers
- Sim
- Simcox
- Simeon
- Simister
- Simke
- Simmerer
- Simmonds
- Simmons
- Simons
- Simper
- Simpkin
- Simpkins
- Simpson
- Sims
- Sinclair
- Sinden
- Single
- Singleton
- Sipthorp
- Sired
- Sjogren
- Skan