Da Ji 妲己 was, according to legend, the consort of the last depraved ruler of the Shang dynasty 商 (17th to 11th cent. BC) , King Zhou 紂.
Da Ji was a daughter of the Lord of Su 有蘇. Because the small country of Su had not delivered tributes, King Zhou attacked Su with his army. In a hopeless situation, the Lord of Su offered King Zhou to present him with his beautiful daughter. The king accepted and withdrew his troops.
King Zhou, fond of wine and women, fell in love with Da Ji to such an extent that he obeyed all her words. His first misdoing was the use of "frivolous music" (yinyue 淫樂), the dances of the northern mile (beibi zhi wu 北鄙之舞), instead of the "correct sounds" (zhengsheng 正聲) normally played at the court. The people suffered under the chaotic administration, and the regional rulers (zhuhou 諸侯) began to rebel.
Da Ji thereupon suggested aggravating punishment in order to demonstrate the authority of the king. Each time Da Ji watched at an execution she burst out laughing. Da Ji is also said to have invented the punishment of the burning pillar (paolao zhi fa 炮烙之法). She also deeply enjoyed the spectacle of of the King's most trusted minister's heart being opened. The royal uncle and minister Bi Gan 比干 was thus cruelly slaughtered because Da Ji desired to see whether his heart really had seven apertures (qi qiong 七窮), as said from the heart of a wise man. King Zhou had a wine pond (jiuchi 酒池) constructed for her and a meat forest (roulin 肉林) created, in which naked men and women pursued pleasure, much to the delight of Da Ji.
When King Zhou's army was defeated by Ji Fa 姬發, the Viscount of the West and eventual King Wu 周武王 of the Zhou dynasty, Da Ji was executed. Yet other sources say that she committed suicide. From the Southern and Northern Dynasties period 南北朝 (300~600) on, Da Ji was interpreted as the incarnation of a nine-tailed fox (jiuweihu 九尾狐), as can be attested in Li Luo's 李邏 commentary to the Qianziwen 千字文. The story figures prominently in the romance Fengshen yanyi 封神演義. Related to this tale is the belief that Da Ji had invented foot binding in order to hide her own small fox feet (Ko 2007: 116).