Millions Knives is the main antagonist of the Trigun series.

He is one of the few fully sentient Plants and Vash's older twin brother. They are both born during a mission to further the human race, raised on a spaceship of settlers with Vash and taken care of by Rem until Knives disrupts the course of the ships, causing them to crash so that humans would not colonize their new home planet. While Vash believes all beings have potential for good and deserve life, Knives believes in the survival of the fittest. After discovering experiments performed on another sentient Plant, he decides that humans are evil, grotesque, and that they need to be eradicated. Vash does not agree with his plans and seeks to stop him, and Knives seeks to dissuade Vash from basing his life around the "idealistic nonsense" preached by Rem. He was unsuccessful in persuading Vash to join his side.

As Trigun unfolds, it becomes apparent that Knives believes that humans are parasites that need to be exterminated. He wants to create a peaceful and fair world with Vash and his other plant brethren, and he believes the only way to do this is by killing off all humans. Knives never claims to be a God; simply a superior being to homosapiens. If Knives were able to kill all humans and begin creating his "Eden" on Gunsmoke, it is very likely that he would act similarly to Vash, as a kind and loving individual.