| Named By: | Marta S. Fernandez in 1999 |
| Time Period: | Middle Jurassic, 171.6-170 Ma |
| Location: | Argentina, Patagonia - Los Molles Formation |
| Size: | Uncertain |
| Diet: | Piscivore, possibly a specialist in squid and belemnites |
| Fossil(s): | Partial skull and vertebrae |
| Classification: | | Chordata | Reptilia | Ichthyosauria | Ophthalmosauridae | Ophthalmosaurinae | |
| Also known as: | | Ophthalmosaurus periallus | |
Mollesaurus is an extinct genus of large ophthalmosaurine ophthalmosaurid ichthyosaur known from northwestern Patagonia of Argentina.