Uther

Uther is a human-turned-Kirby who was Arthas' enemy until Arthas killed Xane, switching to the Undead.

The Chronicles of Uther
When Arthas shattered the big star in the city, he released the worst characters, including Uther, who was trapped in it with the others. While Arthas fought some of the characters he freed from the big star, Uther planned out his first attack.

After a few characters were killed, Uther reveals himself to Arthas, hacking the computer that handles the tournament, forcing Arthas' next opponent to be Kel'Thuzad. While they fight, Uther returns to his lab under the city.

Uther soon sees Kel'Thuzad get killed, and gets frustrated over Arthas' victory, and decides Arthas' old "friend" will fight him next, while at the same time realizing Xane, Arthas' "friend", hasn't been seen in a while.

Uther begins to fight Arthas in their first battle, but turns into a Gordo that Arthas threw to the side while insulting him.