Which Chinese deity is often depicted with a third eye on his forehead?

The Chinese deity often depicted with a third eye on his forehead is Erlang Shen.

Erlang Shen, also called Erlang or Yang Jian in many popular legends, is a warrior god associated with justice, hunting, flood control, and the defeat of demons. His “Eye of Heaven” is commonly said to see through disguises, illusions, and magical transformations. He is usually shown carrying a three-pointed, two-edged spear and accompanied by his hunting dog, Xiaotian Quan.

His identity has layered origins. One tradition connects him with Li Erlang, the son of Qin-era hydraulic engineer Li Bing, whose legends are tied to flood control in Sichuan. Later stories, especially the Ming-dynasty novels Investiture of the Gods and Journey to the West, identify him as Yang Jian, nephew of the Jade Emperor. In Journey to the West, his third eye helps him detect Sun Wukong’s transformations.

A common mix-up is to associate the eye with Sun Wukong because the two famously battle in Heaven. Sun Wukong is the shape-shifting Monkey King; Erlang Shen is the deity traditionally marked by the forehead eye.