Tyrunt are dinosaurian Pokémon, closely resembling theropods such as Tyrannosaurus. Their bodies are grayish-brown, with a lighter gray shade on their bellies and lower jaw. The back comes to a peaked hump, and the tail is short and pointed. They have tiny forelimbs with only two clawed digits, both white. The hind legs are more robust, and its feet feature three white claws and an adjoining rear claw; this fourth digit is stone colored. The front part of each leg also features two, armor-like plates, which are rectangular in shape.
Spiky, white structures, similar to the primitive feathering on many dinosaurs, extend from the back of the neck. Their heads are proportionally large, with a ridged snout and powerful jaws. They have two pointed teeth in the lower jaw, and the upper jaw features tooth-like projections on either side and a slightly-decurved hook at the end. Their large white eyes are semicircular with a black border along the lower curve. Orange, triangular horn-like crests extend from above each eye and point away from the snout, and a similar projection juts out of the tail.
Tyrunt have spoiled and selfish natures. It will throw tantrums and run wild if it encounters something it does not like, and its strong jaws have enough force to shred an automobile. It doesn't seem to realize its own strength; when frolicking with other Pokémon, it tends to unknowingly inflict grave injuries on them while playing. This Pokémon lived 100 million years ago, where theories suggest it might have had a different form then.
A Tyrunt appeared in Pikachu, What's This Key?, where it played a major role. It was a resident of a world full of ice and snow, which was accessed by Pikachu and his friends, courtesy of Klefki's keys.