Spinosaurus
A theropod dinosaur which, due to recent finds, currently holds the coveted title of "biggest meat eating dinosaur", displacing Giganotosaurus, which in turn displaced Tyrannosaurus Rex. 

Spinosaurus was relatively obscure among the general public until it was featured in the film Jurassic Park III, where it replaced the T-Rex as the film's primary antagonist, appearing on JPIII's logo and and killing one in a breif fight near the beginning of the film. This defeat, however, did little to sway the popularity of T-Rex; indeed, many fans reacted negatively to the outcome of the fight. Dinosaur fans often debate the true outcome of such a battle, though in reality it could never take place due to the Spinosaurus and Tyrannosaurus living on different continents and existing millions of years apart from eachother. It is generally thought that the Tyrannosaurus' superior jaw strength would give it an advantage in such a battle. 

However, the depiction of the Spinosaurus in JPIII as an unstoppable superpredator was inaccurate. Its delicate, bony dorsal fin and long, gator-like snout armed with straight, peglike teeth (as opposed to the ribbed, serrated fangs of theropods such as T-Rex), indicate that this beast was a specialised icthyovore as opposed to a hunter of large dinosaurs, growing massive on a diet of fish, as well as pterosaurs, crocodiles and just about anything else it could swallow whole. 

Spinosaurus is closely related to Baryonyx and Suchomimus, but not to the similar looking Dimetrodon, which lived before the age of the dinosaurs.
The Spinosaurus is the biggest theropod.
Spinosaurus is a specialised fish eater.