English: Koleken is an abelisaurid dinosaur from the Late Cretaceous of what is now Argentina. Abelisaurs are large carnivorous theropods known mainly from the southern hemisphere. Distinguishing characteristics include their shortened shouts, and extremely diminished arms. Koleken had rough patches on the top and sides of its skull that may have corresponded to a keratin covering in life, another common feature in abelisaurs. It lived alongside the closely related Carnotaurus, which it resembled, though lacking the large horns.