| Name | Meaning | Gender | Origin |
|---|
| Rocky | rest | Male | English |
| Rolo | Burmese | Unisex | |
| Rootbeer | | Unisex | |
| Rufus | Red haired | Male | Latin |
| Russell | Red as a fox. | Male | |
| Rusty | Covered in rust - a brownish red colour. | Unisex | |
| Sam | to hear | Male | English |
| Sass | Saxon | Unisex | Irish |
| Seal | | Male | |
| Semi | | Unisex | Hebrew |
| Shade | | Male | |
| Sheridan | The Wild Man | Male | Irish |
| Sir | | Unisex | Hebrew |
| Skor | | Unisex | Hebrew |
| Smoke | | Unisex | |
| Smoke | | Unisex | |
| Smokey | A grayish blue colour. Slang for highway patrol officer | Male | |
| Smokey | A grayish blue colour. Slang for highway patrol officer | Male | |
| Smokey | A grayish blue colour. Slang for highway patrol officer | Male | |
| Smudge | A blotch or smear | Male | |
| Snickers | A brand of candy bar. | Unisex | |
| Snickers | A brand of candy bar. | Unisex | |
| Solomon | Wise and peaceful | Male | Hebrew |
| Spike | A long, thick sharp-pointed piece of wood or metal | Male | American |
| Spot | after Data's cat on Star Trek: The Next Generation | Male | |