| Named By: | Munster in 1834 |
| Time Period: | 240-210 Ma Early to Late Triassic |
| Location: | Europe, North Africa, China |
| Size: | 4 meters long |
| Diet: | Piscivore/Carnivore |
| Fossil(s): | Multiple specimens |
| Classification: | | Chordata | Reptilia | Sauropterygia | Nothosauroidea | Nothosauridae | Nothosaurinae | |
| Also known as: | | Chondriosaurus | Conchiosaurus | Conchriosaurus | Dracontosaurus | Dracosaururus | Dracosaurus | Elmosaurus | Kolposaurus | Menodon | Oligolycus | Opeosaurus | Paranothosaurus | Shingyisaurus | |
Nothosaurus ("false lizard", from the Ancient Greek nothos (nothos), "illegitimate", and sauros (sauros), "lizard") is an extinct genus of sauropterygian reptile from the Triassic period, approximately 240-210 million years ago, with fossils being distributed from North Africa and Europe to China. It is the best known member of the nothosaur order.
A complete skeleton of the species Nothosaurus raabi, now a synonym of N. marchicus, can be seen in the Natural History Museum in Berlin.