Jizi or Qizi (, Gija or Kija in Korean) was a semi-legendary Chinese sage who is said to have ruled Gojoseon in the 11th century BCE. Early Chinese documents like the Book of Documents and the Bamboo Annals described him as a virtuous relative of the last king of the Shang dynasty who was punished for remonstrating with the king. After Shang was overthrown by Zhou in the 1040s BCE, he allegedly gave political advice to King Wu, the first Zhou king. Chinese texts from the Han dynasty (206 BCE – 220 CE) onwards claimed that King Wu enfeoffed Jizi as ruler of Chaoxian (朝鮮, pronounced "Joseon" in Korean). According to the Book of Han (1st century CE), Jizi brought agriculture, sericulture, and many other facets of Chinese civilization to Joseon. Gija was Chinese.
Gija (the Korean pronunciation of "Jizi") may have been the object of a state cult in sixth-century Goguryeo, and a mausoleum to him was established in Goryeo in 1102, but the first extant Korean text to mention Gija was the Samguk Sagi (1145). Starting in the late thirteenth century, Gija was fully integrated into Korean history, being described as a successor to the descendants of Dangun in the state of Old Joseon. Following the spread of Neo-Confucianism in Korea in the fourteenth century, scholars of the Joseon Dynasty (est. 1392) promoted Gija as a culture hero who had raised Korean civilization to the same level as China, and Gija became an integral part of Korean cultural identity.
Following the rise of Korean nationalism in the late nineteenth and early twentieth century, however, Korean intellectuals lost their pride in association with Gija and started to doubt the traditional account of his enfeoffment as ruler of Gojoseon. Shin Chaeho (1880–1936) questioned the extent of Gija's cultural contributions, in part because Gija, a Chinese, did not fit into Shin's view of Korean history as the history of the Korean minjok, or "race-nation." Postwar Korean scholars in both North and South Korea have also strongly criticized the story of Gija's migration to Korea in the eleventh century BCE.
His family name was Zi/Ja (子) and given name was Xuyu/Suyu (胥餘/서여 xūyú/seoyeo, or 須臾/수유 xūyú/suyu).