Zant

Zant is the secondary antagonist of Twilight Princess. He probably used to be a high-rank advisor to the twili royal family. After losing at his attempt to ascend the throne as king of the twili, he fled from the castle and had a childish tantrum. He gasped with wonder as Ganondorf's spirit appeared to him, posing as a god. In return for giving him a fraction of his powers, Zant would usurp the throne and become king of the Twili. Then, he would invade and conquer Hyrule. Zant achieved this for Ganondorf and once Ganondorf had been reborn into the world, Zant gave Hyrule to him, in return for being allowed to remain as (usurper) king of the Twili.

It is unkown if Ganondorf would have killed Zant, once he had outlived his usefulness if Link and Midna hadn't done it first.