| Named By: | Fraas in 1866 |
| Time Period: | Late Triassic, 228-201.3 Ma |
| Location: | Germany |
| Size: | Uncertain but estimated around 2.5 meters long |
| Diet: | Carnivore |
| Fossil(s): | Several specimens |
| Classification: | | Chordata | Reptilia | Archosauria | Phytosauria | Phytosauridae | |
| Also known as: | | Belodon kappfi | |
Nicrosaurus (/nekroU'soras/) is an extinct genus of phytosaur reptile existing during the Late Triassic period. It was of medium size, probably about 2.5 m (8.2 ft). Although it looked like a crocodile (and probably lived like the more terrestrial crocodylomorphs), it was not closely related to these creatures, instead being an example of parallel evolution. The main difference between Nicrosaurus (and all other phytosaurs) and modern crocodiles is the position of the nostrils - Nicrosaurus's nostrils, or external nares, were placed directly in front of the forehead, whereas in crocodiles, the nostrils are positioned on the end of the snout. A 2013 study has also found that illium of Nicrosaurus is quite distinctive from all other phytosaurs.
The genus was named by German paleontologist, Dr. Eberhard Fraas, in 1866, possibly after the Neckar river of southwestern Germany, near which it was found.