Nagato

Nagato's pale skin and straight crimson hair betray his Uzumaki roots. In boyhood his fringe hangs over his eyes, hiding the Rinnegan, and once his ninja training begins he sweeps it aside so that only the right eye stays hidden. Bonding with the Outer Path's demonic statue buries black receivers in his back and leaves his frame gaunt and nearly immobile, which is why he passes most of his adult years seated in a mechanical walker, steering the Six Paths from a distance. His Samsara of Heavenly Life Technique bleaches his hair white, and it remains so after his reincarnation, when he is clad in a maroon cloak; drawing in a portion of the Eight-Tails' chakra afterward returns both his red hair and his vigor.

As a boy Nagato cries readily over his own hurts and those of everyone around him. Yahiko urges him to bury that softness, yet Jiraiya recasts it as an asset, insisting it lets him grasp suffering and answer it with kindness. The lesson sticks, and ever after he places other people ahead of himself, first taking up the ninja path to guard Yahiko and Konan and later shouldering what he treats as a duty to rescue the world from its own cruelty. Yahiko's death turns him cold. He convinces himself that killing, even on a large scale, can be excused when it serves a greater end, though he still spares those who yield and grieves fallen allies. Ruling Akatsuki, he wears the Deva Path as a godlike mask while confessing in private that he is nothing more than an ordinary man reaching for peace the only way he knows. Naruto's conviction finally reawakens his buried pacifism and his trust in Jiraiya.

Without either the boy or his parents knowing, Madara Uchiha slips his Rinnegan into the infant Nagato. The Second Shinobi World War later costs him his mother and father, cut down by two Konoha ninja, and his anguish awakens the dojutsu for the first time as he kills them. Orphaned and roaming in search of food, he is found by two other orphans, Konan and Yahiko, and the trio eventually talk Jiraiya into training them. Thanks to the Rinnegan he absorbs every lesson with startling ease.

The three establish Akatsuki as a crusade to end warfare, but Hanzo, who rules Amegakure, springs a trap on them with help from Konoha's Danzo. Holding Konan hostage, he forces a cruel bargain that ends with Yahiko throwing himself onto Nagato's kunai. The tragedy convinces Nagato that only shared agony can push humanity toward peace. Broken in body from the ambush and from bonding with the Outer Path's demonic statue, he takes the name Pain and builds his Six Paths of Pain from a set of corpses, recasting Yahiko's body as the Deva Path and controlling every one of them remotely.

His Rinnegan opens the whole spread of Six Paths Techniques to him, from the Deva Path's gravity to the soul-stealing Human Path and a gateway into the King of Hell, while his Uzumaki blood gives him reserves deep enough to chain its most punishing jutsu in a single day. He claims Amegakure by striking down Hanzo, then runs Akatsuki as a mercenary outfit quietly funded by Obito. Years on, hunting Naruto, he unleashes his Paths on Konoha and flattens much of it before Naruto beats them one after another and traces the trail back to his real body. That meeting turns Nagato around: he spends the last of his strength reviving everyone the assault killed and dies content. Kabuto later drags him back for the Fourth Shinobi World War, and after he is forced against Naruto and Killer B, Itachi's Sword of Totsuka seals him a final time.