| Name | Meaning | Gender | Origin |
|---|
| Ripper | | Unisex | |
| Roo | | Unisex | Hebrew |
| Rosie | From Rose - The most beautiful of flowers | Female | English |
| Roxie | Persian, dawn | Female | English |
| Roxy | From Roxanne - Brilliant dawn | Female | English |
| Ruby | Jewel
| Female | Latin |
| Rusty | Covered in rust - a brownish red colour. | Unisex | |
| Sally | saviour | Female | English |
| Samantha | A listener | Female | Hebrew |
| Sasha | defending men | Female | Russian |
| Schooner | | Unisex | Hebrew |
| Scruffy | Shabby or untidy | Unisex | |
| Shadow | A rough, dark image cast by an object blocking the sun's rays | Female | English |
| Shamrock | | Unisex | |
| Sheba | from Sheba | Female | Hebrew |
| Sheeba | after the cat food | Unisex | |
| Sheila | blind one | Female | Irish |
| Shmoo | | Unisex | Hebrew |
| Sky | The expanse of air over the Earth | Female | Nature |
| Smokie | | Unisex | Hebrew |
| Smoko | | Unisex | Hebrew |
| Smoky | | Unisex | |
| Snickers | A brand of candy bar. | Unisex | |
| Snickers | A brand of candy bar. | Unisex | |
| Snowy | Covered with snow | Unisex | |