| Name | Meaning | Gender | Origin |
|---|
| Pistol | | Unisex | |
| Pixel | | Male | |
| Rambo | | Male | |
| Ranger | dweller in the field A warden employed to protect a forest area. | Male | |
| Remington | from the raven's home | Male | English |
| Rex | after the Rex Banner character in The Simpsons cartoons | Male | Latin |
| Romeo | pilgrim to Rome | Male | Italian |
| Rosco | | Unisex | |
| Ruger | | Unisex | |
| Sarge | Noncommissioned Army or Air Force rank | Male | |
| Sergeant | to serve | Male | Latin |
| Seven | | Male | |
| Sheldon | protected hill | Male | English |
| Smudge | A blotch or smear | Male | |
| Snowy | Covered with snow | Unisex | |
| Sport | One who accepts difficult situations well. | Unisex | |
| Tex | Of Texas | Male | English |
| Thomas | Twin
| Male | Aramaic |
| Thomas | Twin
| Male | Aramaic |
| Thor | Viking mythology: the ruler of the weather | Male | Norse |
| Timmy | From Timothy - Honoring God | Unisex | |
| Toby | God is Good | Male | English |
| Tracker | One who follows the tracks or marks of another. | Unisex | |
| Trigger | | Unisex | |
| Trooper | A state or mounted police officer. Also a member of a cavalry unit. | Unisex | |