Li Deyu  Li Deyu (; 787 – January 26, 850), courtesy name Wenrao (), formally the Duke of Wei (), was an official of the Chinese dynasty Tang Dynasty, serving as a chancellor during the reigns of brothers Emperor Wenzong and Emperor Wuzong and (briefly) their uncle Emperor Xuānzong. He was the leader of the so-called Li Faction in the decades-long Niu-Li Factional Struggles, and was particularly powerful during Emperor Wuzong's reign, dominating the court scene and guiding policies during the campaigns against the crumbling Huigu Khanate and against the warlord Liu Zhen. After Emperor Wuzong's death, Emperor Xuānzong, who had long despised him for his hold on power, had him demoted and banished, where he died in exile. Li Deyu was born in 787, during the reign of Emperor Dezong. His grandfather Li Qiyun () served as the chief imperial censor, and his father Li Jifu would eventually serve as a chancellor during the reign of Emperor Dezong's grandson Emperor Xianzong. It was said that Li Deyu was ambitious in his youth and was studious, particularly concentrating on the "Book of Han" and the "Zuo Zhuan". He, however, did not want to submit to imperial examinations. During Emperor Dezong's "Zhenyuan" era (785-805), when Li Jifu was in exile, Li Deyu accompanied his father and did not seek an official career. During the reign of Emperor Xianzong, Li Jifu became chancellor, and it was said that because Li Deyu wanted to avoid appearance of impropriety, he did not serve at the office of the imperial censors or one of the three main bureaus of the imperial government. Rather, he served on the staff of various regional governors. In 816, after the chancellor Zhang Hongjing left the chancellor post and became the military governor of Hedong Circuit (河東, headquartered in modern Taiyuan, Shanxi), Zhang invited Li Deyu to serve as a secretary. In 819, when Zhang returned to the capital Chang'an to pay homage to the emperor and subsequently remained at Chang'an, Li Deyu was made an imperial censor with the title "Jiancha Yushi" (). In 820, Emperor Xianzong died and was succeeded by his son Emperor Muzong.