| Name | Meaning | Gender | Origin |
|---|
| Slade | Valley | Male | English |
| Sloane | Fighter | Unisex | American English |
| Smidge | | Unisex | Hebrew |
| Smokey | A grayish blue colour. Slang for highway patrol officer | Unisex | English |
| Snickers | A brand of candy bar. | Unisex | English |
| Snowball | | Unisex | Hebrew |
| Snowflake | Single flake or crystal of snow. | Unisex | English |
| Socrates | Uncertain meaning | Male | Greek |
| Solo | | Unisex | Hebrew |
| Solomon | Peace | Male | Hebrew |
| Sonny | Son | Male | English |
| Spanky | | Unisex | Hebrew |
| Sparky | Animated, lively. | Unisex | English |
| Spaz | For a spazy kitty | Unisex | English |
| Speckles | | Unisex | Hebrew |
| Spencer | Someone who gives out goods | Male | French |
| Spidey | | Unisex | Hebrew |
| Spike | A long, thick sharp-pointed piece of wood or metal | Male | English |
| Spirit | Part of the human being associated with the mind. Vigorous or animated state - spirited. Also distilled alcohol. | Unisex | English |
| Spooky | | Unisex | Hebrew |
| Spot | After Data's cat on Star Trek: The Next Generation | Unisex | English |
| Sprinkles | | Unisex | Hebrew |
| Sprite | Lemonade flavored soft drink. | Unisex | English |
| Spunky | Spirited, plucky. | Unisex | English |
| Squeaky | | Unisex | Hebrew |
| Squishy | | Unisex | Hebrew |
| Stanley | Meadow that is stony | Male | English |
| Stardust | | Unisex | Hebrew |
| Starlight | | Unisex | Hebrew |
| Stetson | Son of Stephen | Male | English |