| Name | Meaning | Gender | Origin |
|---|
| Snowman | | Unisex | |
| Snowy | Covered with snow | Unisex | |
| Snuffy | | Unisex | |
| Snuggles | To curl up closely, cuddle | Male | |
| Snuggles | To curl up closely, cuddle | Male | |
| Socks | Short stockings finishing above the ankle | Unisex | |
| Socrates | | Male | |
| Solo | | Unisex | |
| Sonny | A boy or young man. | Male | Nickname |
| Sooki | | Unisex | |
| Sooty | Covered with soot | Unisex | |
| Sox | Short stockings finishing above the ankle | Unisex | |
| Sox | Short stockings finishing above the ankle | Unisex | |
| Spam | | Unisex | Hebrew |
| Spanky | | Unisex | |
| Sparkle | To shine with animation | Unisex | |
| Sparky | Animated, lively. | Unisex | |
| Spaz | For a spazy kitty
| Male | |
| Speedy | Rapid motion, swift. | Unisex | |
| Spider | An eight legged insect | Unisex | |
| Spike | A long, thick sharp-pointed piece of wood or metal | Male | American |
| Spook | | Unisex | |
| Spot | after Data's cat on Star Trek: The Next Generation | Male | |
| Spud | Slang for potato. | Male | |
| Squeak | | Unisex | |