Acristavus is a genus of hadrosaurine hadrosaurid dinosaur. Fossils have been found from the Campanian Two Medicine Formation in Montana and Wahweap Formation in Utah. The type species A. gagslarsoni was named in 2011. Unlike nearly all hadrosaurids except Edmontosaurus, Acristavus lacked ornamentation on its skull. It is closely related to Brachylophosaurus and Maiasaura, and has been placed in a new clade called Brachylophosaurini.