Cheng Yi (1033–1107), also known by various other names and romanizations, was a Chinese classicist, essayist, philosopher, and politician of the Song Dynasty.

He campaigned against the reformist policies of Wang Anshi, and after the reformers were dismissed from office, he was appointed expositor-in-waiting in 1086 to begin lecturing the emperor on Confucianism.

[3] He was more aggressive and obstinate than his brother, and made several enemies, including Su Shi, the leader of the Sichuan group.

[4] In 1452 the title Wujing Boshi (五經博士) was bestowed upon the descendants of Cheng Yi and other Confucian sages such as Mencius, Zengzi, Zhou Dunyi, and Zhu Xi.

[5] A well known chengyu 程門立雪 refers to an incident when two men (Yang Shi and You Zuo) requesting to be taken on as his disciples stood in the snow for hours at his door and became renowned examples of the Confucian virtues of devotion to learning and respect for one's master.