| Named By: | M. J. Polcyn, E. Tchernov & L. L. Jacobs in 2003 |
| Time Period: | 100 Ma |
| Location: | Palestinian Territory |
| Size: | Unavailable |
| Diet: | Carnivore/Piscivore |
| Fossil(s): | Partial remains |
| Classification: | | Chordata | Reptilia | Squamata | Mosasauridae | |
| Also known as: | | Haasia gittelmani | |
Haasiasaurus is an extinct genus of early mosasaur, originally named "Haasia" by M. J. Polcyn et al., in honour of the palaeontologist Georg Haas. (The original name was a junior homonym of Haasia Bollman, 1893, a genus of millipedes.) Haasiasaurus was the largest cenomanian mosasaur at 2.5 metres (8.2 ft). The genus contains the species Haasiasaurus gittelmani, which was found in the Cenomanian 100 million years ago (Upper Cretaceous) rocks near Ein Yabrud, in the Palestinian West Bank, approximately 20 kilometres (12 mi) north of Jerusalem.