|Species :||Tyrannosaurus Rex|
|Time period :||Late Cretaceous 65 million years ago|
|Primary diet :||Carnivore|
|In the series|
|Appearances :||End Game|
He was greyish-brown with white pits and divots on his skull and was red eyes. And if seen closely, is a bit more muscular than his rival, Stumpy.
- It is unknown if Jack is the T. rex's real name, or if it's just a fan made name for him. But it possible that he's real
- Although the main antagonist, his role was small but great.