Daspletosaurus (/dæsˌpliːtəˈsɔːrəs/ das-PLEET-o-SAWR-əs; meaning "frightful lizard") is a genus of tyrannosaurid theropod dinosaur that lived in western North America between 77 and 74 million years ago, during the Late Cretaceous Period. Fossils of the only named species (D. torosus) were found in Alberta, although other possible species from Alberta and Montana await description. Including these undescribed species makes Daspletosaurus the most species-rich genus of tyrannosaur.