| Named By: | Barnum Brown in 1923 |
| Time Period: | Late Cretaceous, 75-67 Ma |
| Location: | Canada - Alberta - Horseshoe Canyon Formation. USA - Montana - Two Medicine Formation |
| Size: | Up to 9.1 meters long |
| Diet: | Herbivore |
| Fossil(s): | Multiple skulls and partial post cranial remains. Eggs and Juvenile specimens also known |
| Classification: | | Chordata | Reptilia | Dinosauria | Ornithischia | Ornithopoda | Hadrosauridae | Lambeosaurinae | |
| Also known as: | | Cheneosaurus | |
Hypacrosaurus (meaning "near the highest lizard" [Greek upo-, hypo- = less + akros, akros, high], because it was almost but not quite as large as Tyrannosaurus) was a genus of duckbill dinosaur similar in appearance to Corythosaurus. Like Corythosaurus, it had a tall, hollow rounded crest, although not as large and straight. It is known from the remains of two species that spanned 75 to 67 million years ago, in the Late Cretaceous of Alberta, Canada, and Montana, United States, and is the latest hollow-crested duckbill known from good remains in North America. It was an obscure genus until the discovery in the 1990s of nests, eggs, and hatchlings belonging to H. stebingeri.