| Name | Meaning | Gender | Origin |
|---|
| Rusty | Rusty, full of rust | Unisex | American English |
| Sage | Aromatic herb | Unisex | English |
| Sammy | His name is God | Unisex | Hebrew |
| Sasha | Defending men | Unisex | Greek |
| Sassy | Lively and spirited | Unisex | English |
| Scout | Observer | Unisex | American English |
| Shadow | Shadow | Unisex | English |
| Shamrock | | Unisex | Hebrew |
| Shorty | Of less than average size | Unisex | English |
| Slim | Slender in proportion to height. | Unisex | English |
| Smokey | A grayish blue colour. Slang for highway patrol officer | Unisex | English |
| Smoky | | Unisex | Hebrew |
| Sparkle | To shine with animation | Unisex | English |
| Sparky | Animated, lively. | Unisex | English |
| Spice | Plant used to flavour food or beverages. | Unisex | English |
| Spirit | Part of the human being associated with the mind. Vigorous or animated state - spirited. Also distilled alcohol. | Unisex | English |
| Spot | After Data's cat on Star Trek: The Next Generation | Unisex | English |
| Squirt | Slang for a small person | Unisex | English |
| Stumpy | A short, thickset person | Unisex | English |
| Sweet | | Unisex | Hebrew |
| Sweetie | Sweetheart. | Unisex | English |
| Sweetpea | | Unisex | Hebrew |
| Tigger | From Winnie the Pooh | Unisex | English |
| Tilly | Powerful battler | Unisex | Germanic |
| Tinker | | Unisex | Hebrew |
| Tiny | Extremely small | Unisex | English |
| Toby | God is good | Unisex | Hebrew |
| Toffee | A hard brown, chewy candy | Unisex | English |
| Tootsie | A girl or young woman. | Unisex | English |
| Twiggy | | Unisex | Hebrew |