Which Dragon King rules the Eastern Sea in Taoist mythology?

The Dragon King who rules the Eastern Sea in Taoist mythology is Ao Guang.

Ao Guang is the Dragon King of the East Sea, one of the Four Dragon Kings who govern the seas and control rain, storms, and waters. He appears in Chinese folk religion and mythology as a powerful sea deity with a palace beneath the ocean.

Ao Guang is especially prominent in the classical novels Fengshen Yanyi and Journey to the West. In the Nezha stories, conflict begins when Nezha’s actions disturb Ao Guang’s undersea realm and lead to the deaths of Ao Guang’s investigator Li Gen and son Ao Bing. The Dragon King then seeks redress from Nezha’s father and the celestial court.

In Journey to the West, Sun Wukong visits Ao Guang’s palace while searching for a weapon. There he obtains the Ruyi Jingu Bang, the magical iron staff later associated with the Monkey King. Ao Guang is often linked with the Azure Dragon, the eastern symbol among the Four Symbols, but that constellation guardian is not simply identical to every version of the Dragon King.