| Name | Meaning | Gender | Origin |
|---|
| Oscar | Divine spear | Male | English |
| Pedro | Stone | Male | Greek |
| Pluto | Wealth, riches | Unisex | Greek |
| Rambo | | Unisex | Hebrew |
| Rebel | One that resists of defies authority | Unisex | English |
| Rex | King | Male | Latin |
| Rogue | | Unisex | Hebrew |
| Roscoe | Roe deer wood | Male | Norse |
| Rufus | Red | Male | Latin |
| Sable | Sable (black) | Unisex | English |
| Sabre | | Unisex | Hebrew |
| Sammy | His name is God | Unisex | Hebrew |
| Samson | Sun | Male | Hebrew |
| Sandy | Defending men | Male | Greek |
| Sasha | Defending men | Unisex | Greek |
| Sasquatch | Has extra toes and hence is a bigfoot | Unisex | English |
| Sassy | Lively and spirited | Unisex | English |
| Satan | The Devil and adversary of God | Unisex | English |
| Saturn | Sixth and second largest planet away from the Sun. | Unisex | English |
| Scooby | | Unisex | Hebrew |
| Scooter | One who goes suddenly and speedily. | Unisex | English |
| Shark | | Unisex | Hebrew |
| Sherlock | With cropped hair | Male | English |
| Snuffles | | Unisex | Hebrew |
| Spencer | Someone who gives out goods | Male | French |
| Stretch | To extend to full length. | Unisex | English |
| Suede | Swedish | Unisex | English |
| Talon | A claw | Male | English |
| Tank | A large metal container. A heavily armed combat vehicle | Unisex | English |
| Tex | Of Texas | Unisex | English |