While there are the famous dragon kings, it is important to realize that there were many dragon kings. Obviously, some were more famous then others. Most dragon kings were responsible for a particular region, although some were given other jobs. The Dragon Kings were usually water-dwelling dragons that were responsible for rainfall and the water in a particular region.
Another common factor in the dragon kings is that they are noted for their beauty and splendor. Most of these dragon kings lived under the water in palaces made of crystal. At their command, there were legions of sea creatures for soldiers and servants.1
However, the dragon kings were not all-powerful. They had to answer to the gods and their emessaries.2 In Korea, the dragon king was not seen as very powerful, but this dragon still granted humans help, favors, and gifts.

Japanese Dragon Kings
The famous Japanese dragon king is Ryo-Wo, who is responsible for the element of water to the Japanese. He holds the Tidal Jewels, which controls the tides of the world. Furthermore, Ryo-Wo is also creditted with giving the Jelly fish its shape, and his daughter, Otohime, was said to have married prince Hoori, a human.5
Ryo-Wo was also revered as the god of the aea, making him quite powerful in the eyes of the Japanese. He is also said to live in a grand palace beneath the waves called Ryugu.6

Created by Nicole