| Name | Meaning | Gender | Origin |
|---|
| Richard | Strong power | Male | French |
| Rocket | To move swiftly and powerfully | Unisex | English |
| Rocky | Battle cry | Male | Germanic |
| Roderick | Famous ruler | Male | Germanic |
| Rogue | | Unisex | Hebrew |
| Rory | Red king | Male | Gaelic |
| Rowdy | Boisterous. Western Nickname. | Unisex | English |
| Ruckus | | Unisex | Hebrew |
| Rush | Red | Male | French |
| Scooter | One who goes suddenly and speedily. | Unisex | English |
| Scratch | | Unisex | Hebrew |
| Serrano | | Unisex | Hebrew |
| Skipper | Master of a Ship | Male | American English |
| Skippy | Master of a Ship | Unisex | American English |
| Skittles | | Unisex | Hebrew |
| Snap | | Unisex | Hebrew |
| Sparky | Animated, lively. | Unisex | English |
| Spaz | For a spazy kitty | Unisex | English |
| Spazz | | Unisex | Hebrew |
| Speedy | Rapid motion, swift. | Unisex | English |
| Spencer | Someone who gives out goods | Male | French |
| Spinner | | Unisex | Hebrew |
| Sprague | High-energy | Male | French |
| Sprint | | Unisex | Hebrew |
| Sprite | Lemonade flavored soft drink. | Unisex | English |
| Spunky | Spirited, plucky. | Unisex | English |
| Sunny | Filled with sunlight | Male | English |
| Taco | A folded fried tortilla filled with meat, cheese and spices. | Unisex | English |
| Tango | | Unisex | Hebrew |
| Thad | Uncertain, perhaps praised or heart | Male | Aramaic |