The Four Kings are a group of boss enemies in Dark Souls. Once the rulers of the highly developed subterranean city of New Londo, each of the Four Kings were entrusted with a fragment of Gywn's Lord Soul. The Kings were later corrupted by the Abyss and Darkstalker Kaathe, who offered the art of Lifedrain to the Kings and their knights, transforming them into Darkwraiths. In an attempt to prevent Kaathe's Darkwraiths and the Four Kings from wreaking havoc upon all of Lordran, the city was flooded by the Keepers of the Seal, killing all of New Londo's residents and sealing the Abyss away beneath the water.
The Seal must first be opened by players in order to gain access to the Abyss, and Ingward, the last remaining Keeper, holds the Key to the Seal. However, only those who learn the art of "Abysswalking" (such as Knight Artorias) can hope to survive the Abyss itself and challenge the Four Kings who dwell in its darkness.
The battle against the Four Kings begins once the player reaches the "floor" of the Abyss. Each of the Four Kings will appear in turn after a certain amount of time has passed. Their attacks range from magic projectiles to powerful area-of-effect attacks. The commonly accepted strategy for fighting the Four Kings is to simply attack quickly and decisively in order to destroy one King before the next appears. Despite their name, it is possible for five or more Kings to appear during this fight.