| First | Last | Nickname | Ht. | Wt. | Reach | Stance | W | L | D | Belt |
|---|---|---|---|---|---|---|---|---|---|---|
| Khalil | Rountree Jr. | 6' 1" | 205 lbs. | 76.0" | Southpaw | 14 | 6 | 0 | ||
| Ronda | Rousey | Rowdy | 5' 7" | 135 lbs. | 66.0" | Orthodox | 12 | 2 | 0 | |
| Ray | Routh | 5' 8" | 185 lbs. | -- | Orthodox | 2 | 1 | 0 | ||
| Roberta | Rovel | Crusher | 5' 8" | 145 lbs. | -- | 4 | 1 | 0 | ||
| Phil | Rowe | The Fresh Prince | 6' 3" | 170 lbs. | 80.0" | Orthodox | 10 | 5 | 0 | |
| Cam | Rowston | Battle Giraffe | 6' 2" | 185 lbs. | 78.0" | Orthodox | 8 | 3 | 0 | |
| Kain | Royer | -- | 185 lbs. | -- | 2 | 2 | 0 | |||
| Brad | Royster | -- | 135 lbs. | -- | 1 | 2 | 0 | |||
| Brandon | Royval | Raw Dawg | 5' 9" | 125 lbs. | 68.0" | Southpaw | 17 | 7 | 0 | |
| Jairzinho | Rozenstruik | Bigi Boy | 6' 2" | 242 lbs. | 78.0" | Orthodox | 15 | 6 | 0 | |
| Mauricio | Rua | Shogun | 6' 1" | 205 lbs. | 76.0" | Orthodox | 27 | 14 | 1 | |
| Murilo | Rua | Ninja | 5' 11" | 185 lbs. | -- | Orthodox | 20 | 13 | 1 | |
| Marco | Ruas | King of the Streets | 6' 1" | 210 lbs. | -- | Orthodox | 9 | 4 | 2 | |
| Rodrigo | Ruas | 5' 10" | 185 lbs. | -- | Orthodox | 4 | 5 | 1 | ||
| Rodolfo | Rubio Perez | Fito | 5' 5" | 145 lbs. | -- | Orthodox | 10 | 16 | 1 | |
| Gabe | Ruediger | Godzilla | 5' 10" | 155 lbs. | -- | Orthodox | 18 | 8 | 0 | |
| Mauricio | Ruffy | 5' 11" | 155 lbs. | 75.0" | Orthodox | 12 | 1 | 0 | ||
| Eddie | Ruiz | 5' 7" | 155 lbs. | -- | Orthodox | 1 | 1 | 0 | ||
| Anthony | Ruiz | El Toro | 6' 2" | 205 lbs. | -- | Orthodox | 33 | 22 | 0 | |
| Paul | Ruiz | 5' 6" | 135 lbs. | -- | 7 | 4 | 0 | |||
| Montserrat Conejo | Ruiz | 5' 0" | 115 lbs. | 61.0" | Southpaw | 10 | 4 | 0 | ||
| Mike | Russow | 6' 1" | 255 lbs. | 73.0" | Orthodox | 15 | 3 | 0 | ||
| Bas | Rutten | El Guapo | 6' 1" | 205 lbs. | -- | Orthodox | 28 | 4 | 1 | |
| Mashrabjon | Ruzibaev | Black Junior | 5' 8" | 155 lbs. | 67.0" | Orthodox | 20 | 4 | 1 |