| Name | Meaning | Gender | Origin |
|---|
| Slim | Slender in proportion to height. | Unisex | English |
| Smoky | | Unisex | Hebrew |
| Solo | | Unisex | Hebrew |
| Sonic | Approaching the speed of sound, fast-paced | Unisex | English |
| Sparky | Animated, lively. | Unisex | English |
| Speedy | Rapid motion, swift. | Unisex | English |
| Spider | An eight legged insect | Unisex | English |
| Spud | Slang for potato. | Unisex | English |
| Spunky | Spirited, plucky. | Unisex | English |
| Squirt | Slang for a small person | Unisex | English |
| Starlight | | Unisex | Hebrew |
| Stretch | To extend to full length. | Unisex | English |
| Stumpy | A short, thickset person | Unisex | English |
| Styx | Myth Name (A River Of The Underworld) | Unisex | English |
| Sweetie | Sweetheart. | Unisex | English |
| Tiny | Extremely small | Unisex | English |
| Titan | Powerful big man | Unisex | Greek |
| Tito | Giant | Unisex | Latin |
| Toby | God is good | Unisex | Hebrew |
| Tootsie | A girl or young woman. | Unisex | English |
| Turbo | Driven by a turbine - turbocharged | Unisex | English |
| Twiggy | | Unisex | Hebrew |
| Twix | Brand of chocolate bar. | Unisex | English |
| Widget | | Unisex | Hebrew |
| Wildfire | | Unisex | Hebrew |
| Winky | | Unisex | Hebrew |