Li Sixun, Wade-Giles romanization Li Ssu-hsün, (born 651—died 716), Chinese painter who was later seen as the chief exponent of a decoratively coloured landscape style of the Tang dynasty and as the founder of the so-called Northern school of professional painters.
Li was related to the Tang imperial family, led an active political life including exile and restoration, and was given the honorary rank of general. His son, Li Zhaodao, was also a famous painter, and thus the father is sometimes called Big General Li and the son Little General Li. While no genuine works survive, both Li Sixun and Li Zhaodao are known to have painted in a highly decorative and meticulous fashion, employing the precise line technique derived from earlier artists such as Gu Kaizhi and Zhan Ziqian, especially adding the decorative mineral colours blue and green (qinglu), often together with white and gold. Chinese theoretician Dong Qichang spoke of a stylistic division between the decorative tradition among Northern painters begun by Li Sixun and the scholarly tradition among Southern school painters begun by Wang Wei.