| Name | Meaning | Gender | Origin |
|---|
| Romeo | Pilgrim to Rome | Male | Italian |
| Roscoe | Roe deer wood | Male | Norse |
| Roxie | Star | Unisex | Persian |
| Rudy | Famous wolf | Male | Germanic |
| Rufus | Red | Male | Latin |
| Rusty | Rusty, full of rust | Unisex | American English |
| Rylee | Rye clearing | Unisex | English |
| Sam | He is called god | Male | Hebrew |
| Sammy | His name is God | Unisex | Hebrew |
| Samson | Sun | Male | Hebrew |
| Sandy | Defending men | Male | Greek |
| Sarge | Noncommissioned Army or Air Force rank | Unisex | English |
| Sasha | Defending men | Unisex | Greek |
| Sassy | Lively and spirited | Unisex | English |
| Scooby | | Unisex | Hebrew |
| Scooter | One who goes suddenly and speedily. | Unisex | English |
| Scout | Observer | Unisex | American English |
| Sexy | | Unisex | Hebrew |
| Shadow | Shadow | Unisex | English |
| Shamus | Supplanter | Male | Hebrew |
| Skittles | | Unisex | Hebrew |
| Skye | Cloud | Male | Norse |
| Snickers | A brand of candy bar. | Unisex | English |
| Snoopy | | Unisex | Hebrew |
| Snowball | | Unisex | Hebrew |
| Sparkey | | Unisex | Hebrew |
| Sparky | Animated, lively. | Unisex | English |
| Spencer | Someone who gives out goods | Male | French |
| Spike | A long, thick sharp-pointed piece of wood or metal | Male | English |
| Taco | A folded fried tortilla filled with meat, cheese and spices. | Unisex | English |