Klorgbane the Destroyer

Klordbane the Destroyer was first seen in Fists of Justice. He was the main antagonist, and he is related to The Guardians of Eternal Youth, as their "evil brother." He has not seen in any other episode. He has to fight Skips every 157 years. His main goal is to defeat Skips, and reign over the Realm as part of the council. He fought Skips for a while, and was ultimately beating him, until he lost to Mordecai and Rigby shortly afterwards.

Appearance
He looks similar to the The Guardians of Eternal Youth, except his clothes are black (opposed to theirs being gold), and his body is more muscular in appearance. He wears a black helmet or hat, a black cape, a black diaper, or pair of underwear, black socks, and two sliver/black bracelets. He also has a red glow around him and carries a red rattle with spikes on it.

Trivia

 * Like The Hammer, he is one of the most powerful characters and/or enemies in the series. The Fists of Justice is the only weapon that can defeat him.
 * He killed one of the Guardians of Eternal Youth, maybe more, but this is unknown.