Krang is a Utrom warlord, and a frequent enemy of both the Ninja Turtles and Shredder. While his history and motives are not explored, Krang appears to be similar to his counterpart in the IDW comic series.
However, he later intervened more directly into the affairs of both the Turtles and Batman when he learned of the Prime Turtles, the original progenitors of all Ninja Turtles throughout the multiverse. Discovering that there was no Krang in their dimension, he believed that killing them would have a ripple effect on other worlds. Furthermore, he intended to merge their world with another multiverse, and to this end, he fought and killed the Anti-Monitor to obtain the technology necessary. He also turned the Anti-Monitor's corpse into an exo-suit.
He then captured both the Prime Turtles and a different Batman, and ordered the activation of the Crisis Tower to merge the worlds. However, his plans were complicated when the progenitor Batman broke himself and the Prime Turtles free, and Raphael escaped with a Mother Box Batman had stolen from Krang.