Bull rancors were a much larger subspecies of rancor that lived on the jungle planet of Felucia, and were known (when prey was scarce) to start eating the giant fungi growing on their home planet (possibly the reason for their size and color). A form of Bull Rancor could also be found on the planet of Dathomir.
Bull rancors were much bigger than a normal rancor and were green in skin color, and they had long arms and hands like an average rancor and they had no toes. The species also had four long curving tusks protruding from their spiky heads, and they had much longer tails than the average rancor that were dragged on the ground. This species of rancor could live up to 1000 years in age, but often died before that when the roots of the horns on their heads entered the brain, causing mental retardation, death, or both.