Four Kings

The Four Kings are a team of bosses in the dark fantasy rpg videogame Dark Souls. They were former rulers of New Londo who got corrupted by the Abyss and turned into evil wraiths.

Story
The Four Kings were once unnamed leaders of New Londo, and, in recognition of their foresight, Lord Gwyn granted them their ranks and apportioned fragments of a Lord Soul discovered from the First Flame. A Primordial Serpent taught the four the art of Lifedrain, which lead them to be corrupted by the abyss.

Their knights became Darkwraiths, users of the art of Lifedrain. In an effort to contain the threat they posed, New Londo was flooded, trapping the Four Kings and the Darkwraiths in the Abyss, and sacrificing the city of New Londo and the countless lives therein.