| Named By: | Nathalie Bardet, Xabier Pereda Suberbiola & NourinEddine Jalil in 2003 |
| Time Period: | Late Cretaceous, 93-89 Ma |
| Location: | Morocco, Errachidia Province |
| Size: | 3 meters long |
| Diet: | Carnivore |
| Fossil(s): | Skull and almost complete post cranial skeleton |
| Classification: | | Chordata | Reptilia | Squamata | Mosasauridae | Russellosaurinae | |
Tethysaurus is an extinct genus of tethysaurine mosasauroid from the Early Turonian (Late Cretaceous) period. The only species is Tethysaurus nopscai.