Naraku was a spider hanyo who was born from the human, Onigumo and various other yokai, and the primary antagonist of the InuYasha series. He was directly responsible for the death of Kikyo 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 Jewel 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 was responsible for nearly all the other character's misery, something he enjoys. However, Naraku himself 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 always manipulated Naraku from the inside of the jewel in order to assure his continued existence.
Once, there was a man named Onigumo, who was full of deceit and hatred for others. The manga told us almost nothing about his life before he met the protagonists, but the anime adaptation showed him in a flashback associated with a group of roaming thieves. It told how he tricked his bandit leader, Rasetsu, into approaching Kikyo and attempting to obtain the Shikon no Tama, or Jewel of Four Souls. However, Onigumo did not warn him that there was a half-demon named Inuyasha, who was keeping a watchful eye over the priestess. Rasetsu survived the encounter with Inuyasha, lost an eye, and returned to his camp only to find that Onigumo had made off with his troops. Rasetsu discovered Onigumo and his troops at an inn down the road celebrating their change in leadership. Enraged, Rasetsu blew up the inn, but the charred body of Onigumo somehow managed to survive the blast. Rasetsu then threw the barely-living Onigumo off a cliff.
By either chance or fate, the badly burned Onigumo was found by Kikyo, who slowly nursed him back to the point of being able to speak. Onigumo developed feelings for Kikyo, but knowing that he could not move for the rest of his life, he summoned countless demons by using his corrupted soul. He then had them devour his body in exchange for giving him a new body with which he could claim Kikyo and the Jewel of Four Souls. Thus the countless demons were bound together in one body with Onigumo serving as a connector. This resulted with Onigumo being reborn as the half-demon, Naraku.
And he is reprised by Paul Dobson in the English dub and Toshiyuki Morikawa in the Japanese dub.