| Name | Meaning | Gender | Origin |
|---|
| Rocko | | Unisex | Hebrew |
| Rogue | | Unisex | Hebrew |
| Rosalyn | Weak, tender or soft horse | Female | Germanic |
| Rosie | Rose | Female | Latin |
| Roxy | Star | Female | Persian |
| Ruby | Red | Female | Latin |
| Rusty | Rusty, full of rust | Unisex | American English |
| Sabre | | Unisex | Hebrew |
| Sadie | Princess | Female | Hebrew |
| Saffron | From the spice or the colour, yellow | Female | English |
| Sammy | His name is God | Unisex | Hebrew |
| Sapphire | Beautiful jewel | Female | Greek |
| Sarah | Princess | Female | Hebrew |
| Sarge | Noncommissioned Army or Air Force rank | Unisex | English |
| Sasha | Defending men | Unisex | Greek |
| Sassy | Lively and spirited | Unisex | English |
| Scooter | One who goes suddenly and speedily. | Unisex | English |
| Scout | Observer | Unisex | American English |
| Shadow | Shadow | Unisex | English |
| Shaggy | Bushy and matted (hair), unkempt. | Unisex | English |
| Shakespeare | Brandish spear | Unisex | English |
| Sheba | Daughter of an oath | Female | Hebrew |
| Shorty | Of less than average size | Unisex | English |
| Simba | Lion | Female | Swahili |
| Slim | Slender in proportion to height. | Unisex | English |
| Smoky | | Unisex | Hebrew |
| Socks | Short stockings finishing above the ankle | Unisex | English |
| Soda | A carbonated water. | Unisex | English |
| Sophia | Wisdom | Female | Greek |
| Sophie | Wisdom | Female | Greek |