Skeletor

Skeletor is the most evil being and most dangerous threat on Eternia. His only goal is power, and to that end he will not rest until he possesses the secrets of Castle Grayskull, whereby he could become master of the universe. This places him in direct conflict with the only man powerful enough to stop him, He-Man.

The character was initially presented simply as an evil demon from another dimension, and in general his origins were not as important as his evil motives. However, the introduction of Hordak as Skeletor's former teacher provided a brief glimpse into a past. Near the end of the original Masters of the Universe franchise, it was hinted that Skeletor might have once been Keldor, the brother of He-Man's father, King Randor. The development of Skeletor's backstory as a dashing, ambitious villain played heavily into his characterization in the 2002 relaunch of the franchise.

Skeletor was one of only a handful of characters that carried over to The New Adventures of He-Man brand, which sent He-Man to the far future to help the Galactic Guardians save the last of humanity from the Evil Mutants. Skeletor follows his enemy, and offers his services to the Mutants simply because he must rid the universe of He-Man.