| Sidnei | Variant of Sidney, meaning 'wide meadow'. |
| Sifis | Variant of Sifis, meaning 'wise' or 'intelligent'. |
| Sifu | Chinese term for a martial arts master or instructor. |
| Sigurjon | Icelandic name meaning 'victory' or 'triumph'. |
| Sik | Short form of Sikh, referring to a follower of Sikhism. |
| Sikki | Variant of Sikh, referring to a follower of Sikhism. |
| Silvian | Man of the Woods |
| Simmie | God has Heard, One who Hears |
| Simmons | God has Heard, One who Hears |
| Simos | Greek name meaning 'listener' or 'hearer'. |
| Sione | Yahweh is Merciful or Gracious |
| Siros | Greek name meaning 'man of the forest'. |
| Sirri | Beautiful Victory |
| Skeets | Quick - Darting |
| Ski | A long runner used for gliding. |
| Skippy | One who moves with light leaps. |
| Slav | Person from Slavic countries or cultures. |
| Slave | A person held in forced service. |
| Smiley | Laughing, Happy |
| Smoke | Visible vapor from a burning fire. |
| Smokey | Resembling Smoke, a Smoky Haze |
| Snyder | One who works as a local tailor. |
| Sojin | Korean name meaning 'wisdom' or 'intelligence'. |
| Soldier | A person serving in an army. |
| Somar | One who is born in summer. |
| Sonn | A variant of the name John. |
| Sono | A name meaning sound or tone. |
| Sorab | Famous Persian Prince, Illustrious |
| Spanky | One who is Outspoken or Stubborn |
| Sparky | Giving off Sparks |
| Spelman | English surname meaning 'blacksmith' or 'metalworker'. |
| Spider | Resembling the Arachnid |
| Spyder | Resembling the Arachnid |
| Stancil | Derived from stone clearing. |
| Stanmore | From the stony moorland. |
| Starlin | A bird of the starling kin. |
| Stefen | Wreath, Crowned |
| Stefin | Variant of Stefan, meaning 'crown' or 'garland'. |
| Stelio | Derived from the Greek star. |
| Stephin | A crown or garland of honor. |