Yang Sifu (楊嗣復) (783–848), courtesy name Jizhi (繼之), nickname Qingmen (慶門), formally Count Xiaomu of Hongnong (弘農孝穆伯), was an official of the Chinese dynasty Tang Dynasty, serving as a chancellor during the reign of Emperor Wenzong and (briefly) the reign of Emperor Wenzong's brother Emperor Wuzong. He was considered one of the leaders of the Niu Faction in the Niu-Li Factional Struggles.