The Dragon Kings are four powerful shinzoku created by Flare Dragon Ceifeed before he immersed himself in the Sea of Chaos after the battle with Ruby Eye Shabranigdu, and was never heard of again. This name for them is not part of canon (see trivia).
Following the end of the Shinma War, each of the Dragon Kings took guardianship over one of the four points of the compass:
- Aqualord Ragradia in the North
- Flarelord Vrabazard in the East
- Airlord Valwin in the West
- Earthlord Rangort in the South
Of the four, the Aqualord is known to be deceased. The Firelord sent a prophecy to his golden dragon servants, to help them find the one who could stop the invasion of Dark Star. Valwin withdraw himself into his Tower of Wind and, with the recent exception of Lina Inverse, it has been centuries since a human has seen him. The condition of the Earthlord is unknown.
During the Kōma War, the section of the continent containing the Aqualord was sealed off from the rest of the world by the mazoku barrier. All of Slayers except for Slayers TRY and Knight of Aqualord takes place within this barrier. Because the Aqualord was destroyed and the other three Dragon Kings were sealed off, humans within the barrier lost the ability to perform holy magic.
Unlike the Five Retainers of Shabranigdu, the Dragon Kings have created no subordinates, although they are served by the ryūzoku instead.
The four Dragon Kings seem to be roughly based on the Four Heavenly Kings from Buddhism.
The term "Dragon King" comes from the names given to Aqualord and Flarelord in the Software Sculptors dub (Water Dragon King and Fire Dragon King, respectively). It is used here because of the lack of a canon name for this group of shinzoku.