Tyrannosaurus is a genus of tyrannosaurid theropod dinosaur. The species Tyrannosaurus rex (rex meaning “king” in Latin), often called T. rex or colloquially T-Rex, is one of the best represented of these large theropods. Tyrannosaurus lived throughout what is now western North America, on what was then an island continent known as Laramidia. Tyrannosaurus had a much wider range than other tyrannosaurids.
It was the last known member of the tyrannosaurids and among the last non-avian dinosaurs to exist before the Cretaceous–Paleogene extinction event.