Yi Ji was a minister of the Three Kingdoms Period that served under Shu. In the Chinese classical novel Romance of the Three Kingdoms, Yi Ji was originally a strategist serving under Liu Biao until he secretly went against his master to warn Liu Bei about the "hex mark" horse and the assassination plot of Cai Mao. Following the death of Liu Biao, Yi Ji officially transferred over to Liu Bei.
In reality, however, none of the stories in the novel was true. It was Zhuge Liang who recommended Sima Hui, Yi Ji, Ma Liang and other scholars who refused to serve in Liu Biao's regime. Yi Ji, like other scholars such as Sima Hui and Ma Liang at the time, were not satisfied with Liu Biao's reign and despite the latter's repeated invitations, Yi Ji and others refused to serve Liu Biao and remained as civilians. After Zhuge Liang became Liu Bei's most trusted subject, one of his accomplishment was to invite Sima Hui, Ma Liang, Yi Ji, and others to come to serve under Liu Bei, and since these scholars respected both Liu Bei and Zhuge Liang, all of them agreed and served in Liu Bei's regime. Yi Ji and most other famous local scholars had never served under Liu Biao's reign. Yi Ji was very skilled with his words. He was one of the five people who constituted the "Shu Ke" (蜀科), the law for Shu Han.