One-Eye is an evil Tyrannosaurus from Speckles the Tarbosaurus aka The Dino King. He serves as the main antagonist of the film. In the movie, he plots to take over the valley and rule it with an iron fist. In order to do that, he started a dinosaur stampede and killed Speckles' brother, Quicks and his twin sisters. He even killed the queen when she challenged him to a fight for the valley. Since then, Speckles vowed revenge and is determine to get stronger to defeat the evil T-Rex and win back the valley. Near the end of the movie, One-Eye paid the price for his evil deeds when two Tylosauruses swam up and devoured him in the ocean.