The Dragon Kings are guardians of rain, who under orders of the Jade Emperor send rain. These are the deities to go to if there is a water shortage in an area. Their true forms are of dragons, but take one human form. The four Dragon Kings are brothers.
Ao Kuang is the Dragon King of the East. The god Lu Ban once went to him to get a blueprint of his palace. Sun Wukong also went to him for a weapon, getting a cudgel. Despite Ao Kuang and Sun Wukong not getting along very well at first, their differences were settled later. He had a son called Ao Ping, who sadly was killed in battled with a being called Nezha.
Ao Chin is the Dragon King of the South. He once gave Sun Wukong a cap.
Ao Jun is of the West. He was once visited by Sun Wukong and later complained to the Jade Emperor about it.
Ao Shun is of the North. He once owned a pair of shoes great for stepping on clouds which was given to Sun Wukong.