Li Tan (李倓) (died 757), known by his princely title of Prince of Jianning (建寧王), posthumously honored as the Prince of Qi (齊王) and then Emperor Chengtian (承天皇帝, literally "the emperor who bore the heaven"), was an imperial prince of the Chinese Tang Dynasty. He was a son of Emperor Suzong who was credited with suggesting to his father the idea of fleeing to Lingwu during the Anshi Rebellion, allowing Emperor Suzong to eventually reestablish a power base and defeat the rebellion. He was also credited with protecting his father on the way to Lingwu. However, he offended Emperor Suzong's favorite concubine Consort Zhang and the powerful eunuch Li Fuguo by accusing them of crimes; in turn, they accused him of having designs on the life of his older brother Li Chu the Prince of Guangping, causing Emperor Suzong to order him to commit suicide. After Li Chu became emperor in 762 (as Emperor Daizong), he posthumously honored Li Tan, first as the Prince of Qi, and then as Emperor Chengtian, to recognize him for his contributions.
Read more about Li Tan: Background, During Anshi Rebellion, Posthumous Recognition