Li Yuanji (李元吉) (603 – July 2, 626), formally Prince La of Chao (巢剌王), more commonly known by the title of Prince of Qi (齊王), nickname Sanhu (三胡), was an imperial prince of the Chinese Tang Dynasty. He was a son of the dynasty's founder Emperor Gaozu of Tang (Li Yuan), and in the intense rivalry developed between his older brothers Li Jiancheng the Crown Prince and Li Shimin the Prince of Qin, he sided with Li Jiancheng and often advocated drastic actions against Li Shimin, including assassination. In 626, Li Shimin, fearing that Li Jiancheng and Li Yuanji were about to kill him, laid an ambush for them at Xuanwu Gate outside the palace and killed them. Li Shimin then effectively forced Emperor Gaozu to yield the throne to him (as Emperor Taizong).

Li Yuanji was born in 603, during the reign of Emperor Wen of Sui. He was the fourth and final son of Li Yuan the Duke of Tang, a hereditary noble, and Li Yuan's wife Duchess Dou, who was herself the daughter of Dou Yi (竇毅) the Duke of Shenwu and Northern Zhou's Princess Xiangyang. He had three older brothers by Duchess Dou -- Li Jiancheng, Li Shimin, and Li Xuanba (李玄霸, who died in 614). She also gave birth to an older sister of Li Yuanji's, the eventual Princess Pingyang.