Er Lang, also known as Erlang or Er Lang Shen and Erlang Shen is a god who is well known for having an opened third eye. He is the nephew of the Jade Emperor and enemy of the god Zhang Xian.
Er Lang is said to be the son of Li Bing (the engineer who is responsible for the irrigation infra-structure Dujiangyan).
Er Lang is also a filial son and a great fighter. Upon his mother died he found his way to the underworld to save his mother from it. He uses his fighting ability to subdue evil spirits, to which the Howling Celestial Dog helps Er Lang. His weapon of choice is a spear.
Er Lang helped his father with the irrigation system and the two had a temple built in their honour.
Li Bing actually sent out his son Er Lang out to find the source of the regions floods, Er Lang spent a year without any success learning of the cause of the floods. It was one time that Er Lang sheltered in a cave and came across a tiger that he slew. Seven hunters who witnessed this agreed to join Er Lang on his quest.
On the outskirts of Guanxian an old woman was found crying, to which the group was told it was due to their grandson being sacrificed to a local river god who had the form of a dragon. Er Lang and the hunters went to the temple of the river god and captured the dragon which freed the region from the floods, finishing Er Lang’s quest as to find out why there was floods.
In Journey to the West, Er Lang is ordered by the Jade Emperor to subdue Sun Wukong who was to be punished for causing havoc in Heaven. Er Lang duels Sun Wukong and eventually defeats Sun Wukong after several transformations plus help from other gods. Er Lang would appear to Sun Wukong as ally rather later on.