| Named By: | Edward Drinker Cope in 1877 |
| Time Period: | Late Cretaceous-Eocene |
| Location: | Canada and the USA. Some fossil remains also reported from France |
| Size: | Depending upon the species, anywhere between 1.5 and 3.5 meters long |
| Diet: | Carnivore/piscivore |
| Fossil(s): | Many individuals, some almost complete |
| Classification: | | Chordata | Reptilia | Choristodera | Champsosauridae | |
| Also known as: | | Champsosaurus annectens | Champsosaurus australis | Champsosaurus brevicollis | Champsosaurus inelegans | Champsosaurus inflatus | Champsosaurus profundus | Champsosaurus puercensis | |
Champsosaurus is an extinct genus of diapsid reptile belonging to the order Choristodera.