| Name | Meaning | Gender | Origin |
|---|
| Speedy | Rapid motion, swift. | Unisex | |
| Spencer | Shopkeeper, dispenser, keeper | Male | English |
| Spike | A long, thick sharp-pointed piece of wood or metal | Male | American |
| Spooky | | Unisex | |
| Squeak | | Unisex | |
| Squiggle | | Unisex | |
| Stanley | Lives by the stony grove
| Male | English |
| Steve | garland, crown | Male | English |
| Stewie | | Unisex | |
| Storm | Storm
| Male | Word |
| Stripe | | Unisex | |
| Styx | from Greek mythology, the river that formed the boundary between earth and the underworld | Unisex | |
| Sunny | Abounding in sunshine, cheerful | Male | Nickname |
| Sushi | Raw fish. | Unisex | |
| Sushi | Raw fish. | Unisex | |
| Sweetie | Sweetheart. | Male | |
| Syd | Variant of Sidney from St. Denis
| Male | |
| Sylvester | A cartoon cat that tried to eat the bird character Tweety. He was a black and white cat.
| Male | Latin |
| Tabasco | American spicy sauce made from red peppers. | Male | |
| Tabby | | Unisex | |
| Taffy | Sticky candy | Male | Welsh |
| Tango | | Male | |
| Tank | A large metal container. A heavily armed combat vehicle | Unisex | |
| Tanner | leather worker | Male | English |
| Tarzan | | Male | |