In Chinese mythology, Chi You (蚩尤; pinyin: chi1you2) or Chi Woo in Korean, is a war deity and for Korean, a mythical emperor of ancient Korea as well. For the Miao (Hmong) people, Chi You is also seen as a sagacious mythical king.

Chi You was the mythical leader of the Paedal or Guryeo people in Korea and eastern China. According to Chinese history record Records of the Grand Historian, Chi Woo, along with his 81 brothers, was a grotesque looking creature: he had six arms, four eyes, the head and hooves of an oxen and his head was made from metal. He only ate stones and pebbles, therefore his teeth were almost unbreakable.

One of his achievements was the first use of metal weapons in warfare. He is said to have forged the first swords from bronze or copper. He was violent and no one could defeat him.

Here, records about Chi Woo are controversal. According to Chinese records, Chi Woo plotted to rebel against Huang Di. His troops consisted of Giants, Guryeo people and evil spirits; they fought with Huang Di's army at Zhuolu plains.

Both sides used magical powers, but Chi Woo had the advantage because his troops were armed with forged swords and halberds. Using his power (perhaps a mythological explanation of meteorology used in warfare), Chi Woo covered the battle field in thick fog. Only with the help of a magical compass chariot could Huang Di's troops could find their way through the mist. He also used his daughter Nü Ba , the Goddess of Drought, to harm Chi You's troops. Later on, Chi Woo suffered more defeats and was captured. Only Ying Long, the winged dragon, being a brave servant of Huang Di, dared to slay him. Chi You's chains were transformed into acorn trees, while Ying Long was cursed to remain on earth forever.

In Korean records, including controversal Hwandan Gogi , and a few Chinese records, however, portrayal of Chi Woo is completely different. The records describes Chi Woo as the Emperor and goes on to say that it was Huang Di who rebelled against Chi Woo. Chi Woo moved his troops to the west and conquered 21 states in two years, and Huang Di, summoning his vassals, challenged Chi Woo at Zhuolu plain. The records tells that the war went on for 10 years, and that eventually Chi Woo defeated Huang Di. As for supposed death of Chi Woo during war, the recoreds explain that it was one of his generals, Chi Woo Bi, who resembled Chi Woo in physical appearance. Chi Woo Bi supposedly was rushing for victory and recklessly charged into Huang Di's army. Hearing his general's death, Chi Woo charged his troops to final battle, which culmulated in Chi Woo's victory and Huang Di was driven to western side of China.

The records almost universally writes that Chi Woo's grave is in present Shandong province of China, and that in July, the red flag, the symbol of Chi Woo's army appeared on top of his grave.

Yet Chi You was not only described as a Korean deity; most Chinese sources actually describe him as a Miao deity. He is also among the three main deities (the others being Huang Di and Yan Di) worshipped by certain Miao. According to this legend, Chi You is a leader of the Miao who was once a follower of Yan Di. When Huang Di subdued Yan Di, Chi You was weary of the supression and conspired with Yan Liang, another deity. Soon, Miao and Han clashed in the battle of Zhuolu. Actually, this version of the myth is more common, while the first one is rather controversial and should be seen as a result of Korean nationalist movements. Like the Koreans, the Miao often depict Chi You as a wise ruler, not as a fierce barbarian warlord (or even monster).