Naraku

Naraku was a spider hanyō who was born from the human, Onigumo and various other yōkai, and the primary antagonist of the InuYasha series. He was directly responsible for the death of Kikyō and the seal placed on Inuyasha. Naraku desired the Shikon no Tama, a jewel that would be able to grant him near-invincibility should he acquire all the pieces of it. He desired the jewel to purge his half-human self from his body, and enhance his strength even further. Close to the end of the story Naraku gained all Shikon shards and made the Shikon no Tama whole again which resulted in Naraku transformed himself into a full-Spider yōkai shortly before his defeat and death by Inuyasha's hands.

He is responsible for nearly all the other character's misery, something he enjoys. However, Naraku himself has never found happiness. In the epilogue, after his death, the Demon of the Shikon no Tama became the last enemy of Inuyasha inside the jewel, because he had always manipulate him from the inside of the jewel in order to assure his continued existence.