Lady Mi was the second wife of the warlord Liu Bei, who lived in the late Eastern Han dynasty and Three Kingdoms period of China. She was from Qu County (朐縣), Donghai Commandery (東海郡), which is present-day Lianyungang, Jiangsu. She had two brothers: Mi Zhu and Mi Fang, who previously served the warlord Tao Qian before joining Liu Bei's side. Mi Zhu married his sister to Liu Bei after Liu's wife and children (identities unknown) were captured by Lü Bu when Lü invaded Xiapi in 196.
In 219, Lady Mi's brother (Mi Fang) was left in charge to defend key bases in Jing Province – Nan Commandery (南郡; around present-day Jingzhou, Hubei) and Gong'an County. Lu Meng convinced him to surrender and betrayed Guan Yu. Liu Bei's treatment of Lady Mi which he may have seen as unfair could have been a factor in his decision to surrender to Wu.
In the 14th-century historical novel Romance of the Three Kingdoms, during the Battle of Changban, Lady Mi was lost in the midst of the battle and was injured while carrying Liu Bei's infant son Liu Shan with her. Zhao Yun went to search for them and found them beside a well. Zhao urged her to follow him but she refused, not wishing to burden him. After entrusting Liu Shan to Zhao, Lady Mi committed suicide by throwing herself into the well. Zhao knocked down a wall to cover the well to prevent their pursuers from finding her body.
A poem honored her sacrifice with those lines: The embattled captain had to have his steed; On foot he could not save the little prince. Her death preserved the Liu dynastic line: For bold decision mark this heroine.
Later on, when Guan Yu met Liu Bei after they escaped with Lady Gan and saw that Lady Mi was absent, he asked his brother why he couldn't see his other sister in law. Liu Bei could only recount her heroic sacrifice to save Liu Shan in Dangyang. Guan Yu sighed and told him "Had you let me kill Cao Cao on the hunting field at XuChang, you might have spared yourself theses woes." Xuande replied "I had to consider how such an act could injure us."