| Name | Meaning | Gender | Origin |
|---|
| Snickers | A brand of candy bar. | Unisex | |
| Snickers | A brand of candy bar. | Unisex | |
| Snoopy | | Male | |
| Snowy | Covered with snow | Unisex | |
| Socks | Short stockings finishing above the ankle | Unisex | |
| Sooty | Covered with soot | Unisex | |
| Sophia | Wisdom.
| Female | Greek |
| Sophie | Wisdom. Variant of Sophia
| Female | |
| Sox | Short stockings finishing above the ankle | Unisex | |
| Sox | Short stockings finishing above the ankle | Unisex | |
| Soxy | | Unisex | |
| Speckles | | Unisex | Hebrew |
| Spike | A long, thick sharp-pointed piece of wood or metal | Male | American |
| Splotch | An irregularly shaped spot | Unisex | |
| Spot | after Data's cat on Star Trek: The Next Generation | Male | |
| Spotty | Marked with spots | Unisex | |
| Streak | | Unisex | |
| Stripes | | Unisex | |
| Stubby | | Unisex | |
| Sundae | | Unisex | |
| Sushi | Raw fish. | Unisex | |
| Sushi | Raw fish. | Unisex | |
| Susie | Hebrew, lily | Female | English |
| Suzie | | Female | |
| Sylvester | A cartoon cat that tried to eat the bird character Tweety. He was a black and white cat.
| Male | Latin |