| Name | Meaning | Gender | Origin |
|---|
| Sassy | Lively and spirited | Unisex | English |
| Scooby | | Unisex | Hebrew |
| Scooter | One who goes suddenly and speedily. | Unisex | English |
| Scout | Observer | Unisex | American English |
| Shadow | Shadow | Unisex | English |
| Shady | | Unisex | Hebrew |
| Shaggy | Bushy and matted (hair), unkempt. | Unisex | English |
| Shelly | Clearing near a ledge | Unisex | English |
| Shiloh | Gift for him | Unisex | Hebrew |
| Shorty | Of less than average size | Unisex | English |
| Silky | Soft as silk. | Unisex | English |
| Skeeter | | Unisex | Hebrew |
| Skinny | | Unisex | Hebrew |
| Skippy | Master of a Ship | Unisex | American English |
| Skittles | | Unisex | Hebrew |
| Sky | Sky | Unisex | Norse |
| Skyler | Guarded | Unisex | Dutch |
| Slinky | | Unisex | Hebrew |
| Sly | A forest | Unisex | Latin |
| Smokey | A grayish blue colour. Slang for highway patrol officer | Unisex | English |
| Smudge | A blotch or smear | Unisex | English |
| Snickers | A brand of candy bar. | Unisex | English |
| Snoop | To pry into the private affairs of others | Unisex | English |
| Snoopy | | Unisex | Hebrew |
| Snowball | | Unisex | Hebrew |
| Snowflake | Single flake or crystal of snow. | Unisex | English |
| Snuffles | | Unisex | Hebrew |
| Snuggles | To curl up closely, cuddle | Unisex | English |
| Spanky | | Unisex | Hebrew |
| Sparkle | To shine with animation | Unisex | English |