| Name | Meaning | Gender | Origin |
|---|
| Sarah | Princess | Female | Hebrew |
| Sarge | Noncommissioned Army or Air Force rank | Unisex | English |
| Sasha | Defending men | Unisex | Greek |
| Sassy | Lively and spirited | Unisex | English |
| Scarlett | Scarlet | Female | English |
| Scooter | One who goes suddenly and speedily. | Unisex | English |
| Scout | Observer | Unisex | American English |
| Shadow | Shadow | Unisex | English |
| Shaggy | Bushy and matted (hair), unkempt. | Unisex | English |
| Shea | Hawklike - graceful, free, courageous | Male | Gaelic |
| Sheba | Daughter of an oath | Female | Hebrew |
| Sherlock | With cropped hair | Male | English |
| Shorty | Of less than average size | Unisex | English |
| Silly | | Unisex | Hebrew |
| Simba | Lion | Female | Swahili |
| Skipper | Master of a Ship | Male | American English |
| Smoky | | Unisex | Hebrew |
| Snow | Snow, fair skinned | Female | English |
| Socks | Short stockings finishing above the ankle | Unisex | English |
| Soda | A carbonated water. | Unisex | English |
| Sophia | Wisdom | Female | Greek |
| Sophie | Wisdom | Female | Greek |
| Sparky | Animated, lively. | Unisex | English |
| Spaz | For a spazy kitty | Unisex | English |
| Spike | A long, thick sharp-pointed piece of wood or metal | Male | English |
| Spot | After Data's cat on Star Trek: The Next Generation | Unisex | English |
| Spring | To burst forth | Female | English |
| Sprite | Lemonade flavored soft drink. | Unisex | English |
| Squirt | Slang for a small person | Unisex | English |
| Stumpy | A short, thickset person | Unisex | English |