| Name | Meaning | Gender | Origin |
|---|
| Shorty | Of less than average size | Unisex | English |
| Skeeter | | Unisex | Hebrew |
| Skittles | | Unisex | Hebrew |
| Sky | Sky | Unisex | Norse |
| Smiley | | Unisex | Hebrew |
| Smudge | A blotch or smear | Unisex | English |
| Snickers | A brand of candy bar. | Unisex | English |
| Sniper | A skilled shooter who spots targets from a concealed place. | Unisex | English |
| Snookums | | Unisex | Hebrew |
| Snuggles | To curl up closely, cuddle | Unisex | English |
| Sonic | Approaching the speed of sound, fast-paced | Unisex | English |
| Spanky | | Unisex | Hebrew |
| Sparky | Animated, lively. | Unisex | English |
| Spaz | For a spazy kitty | Unisex | English |
| Speedy | Rapid motion, swift. | Unisex | English |
| Spirit | Part of the human being associated with the mind. Vigorous or animated state - spirited. Also distilled alcohol. | Unisex | English |
| Spunky | Spirited, plucky. | Unisex | English |
| Squeaker | | Unisex | Hebrew |
| Squeakers | | Unisex | Hebrew |
| Squeaky | | Unisex | Hebrew |
| Squirt | Slang for a small person | Unisex | English |
| Sticky | | Unisex | Hebrew |
| Taco | A folded fried tortilla filled with meat, cheese and spices. | Unisex | English |
| Taz | Wild Animal, Thrid Born | Unisex | American |
| Teeny | | Unisex | Hebrew |
| Thumper | To walk with heavy steps | Unisex | English |
| Tinkerbell | | Unisex | Hebrew |
| Tiny | Extremely small | Unisex | English |
| Tootsie | A girl or young woman. | Unisex | English |
| Topsy | On top | Unisex | English |