The bull rancor represented a significantly larger subspecies compared to the standard rancor. These creatures were commonly encountered on the jungle world of Felucia. It's speculated that their considerable size and unique coloration could be attributed to their diet of giant fungi, a necessity when typical prey was scarce. A variation of the bull rancor also existed on the mountainous planet of Dathomir.
Distinguishing features of the bull rancor included its lighter-colored skin, an extended tail, and, in the case of males, prominent horns that grew from their enormous heads. These generally solitary beings posed a great threat, even to other rancors. They fiercely guarded the renowned "rancor graveyard" located on Felucia. They were known to exhibit greater aggression than females and subordinate males. The Felucians held the belief that capturing or taming them was impossible. While their armor was exceptionally durable, their eyes and mouth were particularly vulnerable. However, a lightsaber could easily cut through its hide.
Following the demise of her master, Padawan Maris Brood began succumbing to the influence of the dark side of the Force, developing a profound connection with a bull rancor on Felucia. This creature became her cherished "pet," displaying unwavering loyalty and willingness to defend her at all costs. Upon capturing Senator Bail Prestor Organa, she cautioned him against attempting escape, emphasizing the bull rancor's intense hunger. When Galen Marek returned to the planet to rescue the Senator, Maris dispatched the bull rancor to intercept him. However, the Sith apprentice ultimately defeated the creature by unleashing Force lightning into its mouth, followed by a fatal lightsaber strike to the back of its head. Later, during a confrontation with Maris Brood in the dense Felucian jungle, near the sarlacc pit where Shaak Ti met her end, Galen Marek faced another bull rancor sent to stop him, but this one also perished.
A notable inconsistency exists between the bull rancors featured in Star Wars Galaxies and those in The Force Unleashed. The Galaxies versions bear a closer resemblance to standard rancors, a trait also observed in the bull rancor depicted in the Star Wars Galaxies Trading Card Game. This discrepancy might be attributed to the potential warping effect of the dark side of the Force on Maris Brood's bull rancor, as well as on Brood herself.
Furthermore, differences can be observed in the portrayal of Maris Brood's bull rancor between the Wii/PS2 and PS3/XBox360 versions of The Force Unleashed video game. The Wii/PS2 version depicts the bull rancor as significantly larger than its PS3/XBox360 counterpart. In the DS version, the bull rancor serves as a sub-boss encountered during the initial mission on Felucia. During the fight with Maris Brood, she is riding a regular rancor.