Ansem the Seeker of Darkness

Ansem, the Seeker of Darkness (voiced by Billy Zane, and Richard Epcar in the sequels) is Xehanort's Heartless and the main antagonist of the first Kingdom Hearts game. He called himself "Ansem" after his former master, Ansem the Wise. This Ansem's goal was to spread the darkness and have it conquer all worlds. He even tricked Riku into opening his heart to the darkness, allowing Ansem to take over his body. But his plan failed when Sora, Donald, and Goofy stopped him, and he was defeated by the light.