| Named By: | Friedrich von Huene in 1932 |
| Time Period: | Middle Jurassic |
| Location: | England, Dorset - Inferior Oolite |
| Size: | Roughly estimated to be around 4 meters long, possibly slightly bigger |
| Diet: | Carnivore |
| Fossil(s): | Partial post cranial remains and lower jaw, possibly of a juvenile |
| Classification: | | Chordata | Reptilia | Dinosauria | Theropoda | Megalosauridae | |
| Also known as: | | Megalosaurus nethercombensis | Megalosaurus lydekkeri | Eustreptospondylus | Sarcosaurus | |
Magnosaurus (meaning 'large lizard') was a genus of basal tetanuran theropod dinosaur from the Middle Jurassic of England. It is based on fragmentary remains and has often been confused with or included in Megalosaurus.