"So you have come this far, and still you understand nothing. Every light must fade, every heart return to darkness!" -Ansem to Sora.
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. To do this, he used Maleficent and the other Disney villains to gather the seven Princesses of Heart to open the Keyhole to the Door to Darkness. 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 of Kingdom Hearts.
But because he took control of Riku, a small piece of Ansem still existed within him. Riku fought him in Castle Oblivion and was victorious.
- Jaden will face Xehanort's Heartless for the first time in The Jaden Sora Power Hour.
- Ansem will become Aaron's enemy in Aaron's Adventures in Kingdom Hearts
- Ansem has his powerful shadow that becomes a guardian for defense.
- When Xehanort's Heartless was born, his remaining body became Xemnas, Xehanort's Nobody.
- Because Ansem was born from the heart of Master Xehanort, his clothes are extremely similar to his original incarnation's standard attire
- Ansem is the one responsible for turning Lucifer into the Lord of all The Dark Ones.
- Ansem will appear in Jeffrey, Jaden & Friends' Storm Adventures of Kingdom Hearts: Dream Drop Distance, and it is revealed that Ansem is the one who gave Young Xehanort the ability to travel through time.
- Ansem will become Hiccup's enemy in the future.
- Ansem will become Twilight's enemy in Twilight's Adventures of Kingdom Hearts.