A Centrosaurus (sometimes called monoclonius) is a ceratopsian dinosaur, a member of the family best known for the triceratops. While the triceratops has three horns, the centrosaur has a single large horn on its nose, two smaller horns on its frill, and a pair of short horns pointing up over the eyes (the latter probably for defensive purposes). Like all ceratopsians, the armor class of the centrosaurus depends on whether the attacker is in front of the creature, behind, or beside it.

They are aggressive toward interlopers, attacking anyone who might appear to be a threat. These creatures are about 18 feet long and weigh about 12,000 pounds (6 tons).