Hades

Hades is a villain from the Kingdom Hearts series.

In Kingdom Hearts
Hades was one of Maleficent's co-conspirators. He utilized the Heartless by supplying them as monsters to the Olympus Colisseum, for heroes to battle as per usual. However, he also gained the assistance of Cloud Strife by making a deal: If Cloud kills Hercules, Hades will lead him to Sephiroth (who he apparently does know the location of, as Sephiroth is indeed at the colisseum). Hades additionally provided Sora with a pass to enter the colisseum games. However, when Sora appeared to be winning in the Colisseum, Hades instructed Cloud to kill Sora as well. When the plan failed (either with Cloud refusing to deal the final blow to Sora, or with Sora defeating Cloud; it depends on the result of the battle), Hades had Cerberus kill Cloud. However, Hercules rescued Cloud and Sora defeated Cerberus.

As Sora left the Colisseum, Maleficent warned Hades not to be overcome by the darkness. Although Hades sent Maleficent away, claiming he could handle it, he ironically was not overcome at all (while the rest of Maleficent's followers and Maleficent herself ended up being overcome, with the other exception of Captain Hook). Also ironically, he outlived Maleficent.

When Hades learned of Maleficent's demise, he put matters into his own hands. Hades, determined on personally defeating both Hercules and Sora, opened the Hades Cup in the Colisseum. The long, grueling tournament had a battle with him near the end. Unfortunately for Hades, Sora defeated him in the battle. After a few more battles in the cup, though, Hades decided on a way for revenge.

In events very much like those in Hercules, Hades unleashed the four Titans upon the world (although only two are seen, it can be guessed that the other two and possibly the Cyclops were as well). When Sora reached the final rank in the tournament, he had to combat the Rock Titan. Upon its defeat, Hades apparently went into hiding.