The bull rancor is a subspecies of rancor in the Star Wars universe. Appearing in the games Star Wars Galaxies and Star Wars: The Force Unleashed, these creatures are said to be even more ferocious than the standard rancor. This breed of rancor could be found on the planet Felucia.
The bull rancor was marked by its paler flesh, elongated tail and the males' immense horns that sprouted from their massive heads. These generally solitary creatures were incredibly dangerous, even to other rancors, and guarded the legendary "rancor graveyard" on Felucia. They were noted to have been much more aggressive than the females, and lesser male kindred, and the Felucians believed that they were incapable of being captured or tamed. They had extremely tough armour, but the eyes and mouth were two major weak points.
After the death of her master, Padawan Maris Brood began to slip to the dark side of the Force, whereupon she formed a strong bond with a bull rancor on Felucia. The creature became her new "pet" and was intensely loyal to Maris, willing to fight to the death to protect her. When she captured Senator Bail Organa, she warned him not to escape, as the bull rancor was "very hungry." When Galen Marek came to the planet again to free the Senator, Maris sent forth the bull rancor to stop him. However, the creature was slain by the Sith apprentice when he exploited the weakness in its armour.