Emperor Xianzong of Tang (778 –February 14, 820; r. 805 – 820), personal name Li Chun, né Li Chun, is an emperor of the Chinese Tang Dynasty.

He is the eldest son of Emperor Shunzong, who reigns for less than a year in 805 and who yields the throne to him late that year.

Once emperor, Emperor Xianzong sets out to curb the power of the military governors (Jiedushi), and, when they will not heed his orders, he wages wars against them.

His initial campaigns are quite successful, and Xianzong's army defeats warlords such as Liu Pi, Yang Huilin in 806 and Li Qi in 807.

In 813, after the submission of one of the key holdouts, Weibo Circuit (headquartered in modern Handan, Hebei) under Tian Xing, Emperor Xianzong appears poised to reunite the empire, many parts of which had effectively been ruled independently by regional warlords.

Xianzong's first setback is in 813, when he fails to defeat military governor Wang Chengzong.

However, by 817, after the defeat of Li Shidao and Wang's submission, all of the empire is under imperial authority again.

Later historians refer to Emperor Xianzong's reign as the Yuanhe Restoration.

Emperor Xianzong's reign briefly stabilizes Tang from the destructive forces of the military governors, but sees the rise of the power of eunuchs.

Emperor Xianzong himself is allegedly murdered by the eunuch Chen Hongzhi in 820.

(There are nagging suspicions, never proven, that Xianzong's wife Consort Guo and her son Li Heng (who succeeds Xianzong as Emperor Muzong) are involved.)