| Named By: | Thomas Carr, Thomas Williamson & David Schwimmer in 2005 |
| Time Period: | Late Cretaceous, 77 Ma |
| Location: | USA, Alabama, Demopolis Chalk Formation |
| Size: | Juvenile specimen 7 meters long |
| Diet: | unavailable |
| Fossil(s): | One partial skeleton of a juvenile |
| Classification: | | Chordata | Reptilia | Dinosauria | Saurischia | Theropoda | Tyrannosauroidea | |
Appalachiosaurus ( ap-a-LAY-chee-o-SAWR-as; "Appalachian lizard") is a genus of tyrannosauroid theropod dinosaur from the Late Cretaceous Period of eastern North America. Like almost all theropods, it was a bipedal predator. Only a juvenile skeleton has been found, representing an animal over 7 meters (23 ft) long and weighing over 600 kilograms (1300 lb), which indicates an adult would have been even larger. It is the most completely known theropod from the eastern part of North America.
Fossils of Appalachiosaurus were found in central Alabama, from the Demopolis Chalk Formation. This formation dates to the middle of the Campanian stage of the Late Cretaceous, or around 77 million years ago.