| Name | Meaning | Gender | Origin |
|---|
| Shakespeare | Brandish spear | Unisex | English |
| Shorty | Of less than average size | Unisex | English |
| Shredder | | Unisex | Hebrew |
| Slim | Slender in proportion to height. | Unisex | English |
| Snoopy | | Unisex | Hebrew |
| Snowball | | Unisex | Hebrew |
| Snuffles | | Unisex | Hebrew |
| Socks | Short stockings finishing above the ankle | Unisex | English |
| Spanky | | Unisex | Hebrew |
| Sparky | Animated, lively. | 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 |
| Squeakers | | Unisex | Hebrew |
| Squeaky | | Unisex | Hebrew |
| Squirt | Slang for a small person | Unisex | English |
| Sticky | | Unisex | Hebrew |
| Stinker | | Unisex | Hebrew |
| Tank | A large metal container. A heavily armed combat vehicle | Unisex | English |
| T-bone | A thick steak containing a T shaped bone. | Unisex | English |
| Teaser | | Unisex | Hebrew |
| Terminator | | Unisex | Hebrew |
| Tiger | Tiger | Unisex | English |
| Tilly | Powerful battler | Unisex | Germanic |
| Tiny | Extremely small | Unisex | English |
| Tizzy | | Unisex | Hebrew |
| Trouble | A cause of disturbance or difficulty. | Unisex | English |
| Turbo | Driven by a turbine - turbocharged | Unisex | English |
| Twinkie | A cream filled cake. | Unisex | English |
| Waffles | | Unisex | Hebrew |
| Whiskers | | Unisex | Hebrew |