E750

Appearance
It has a charcoal black color with the iconic Velociraptor sickle claw, quills down its tail, a head that is a mixture of Indominus rex and Indoraptor. It has a red eye as seen in the teaser trailer. It has spikes down its back and has the arms and claws of the Indominus rex. In the slowed down trailer, it is seen that the Scorpius rex can apparently camouflage.

Season 1
The animal is first mentioned in Season 1 during Brooklynn's search through Henry Wu's computer, a folder labeled "E750 Clinical Trial Results". Also on that computer screen, there are multiple dinosaur skeletons showcased, including Spinosaurus and Tyrannosaurus; these are most likely its hybrid components. Later in the season, Eddie indirectly references E750 when he was telling the kids that Wu was creating monsters that nobody knew about.

Season 2
In Season 2, Kenji Kon repeatedly clicked a button that short-circuited the creature's containment tube, causing the cryogenic chamber to heat up and crack open.

After the deaths of Mitch and Tiff, a Compsognathus ripped through a cable which contributed to keeping it frozen. E750's screech/roar is later heard as the screen goes black, presumably as it breaks free, roaming through the island. At some point, its red eye sees lightning strike a tree and set it on fire.

There may have been many attempts to create the Scorpius Rex, as the notes that Brooklynn holds in "The Watering Hole" had incrementing numbers on each page: 1309, 1310, 1311 and, much later in notes, E750. Pages 1309 and 1310 show combinations of the letters used in DNA sequences, but are not grouped as DNA sequences.

Season 3 Official Trailer
In the official trailer of season 3, it is mentioned that E750 is a failed version of the Indominus rex, so it could possibly be the oldest Jurassic World hybrid. It is also seen attacking Dr. Wu in some of his logs, and is most likely a baby E750 or just a fake plush/toy