Emperor Ruizong of Tang (22 June 662 – 13 July 716), personal name Li Dan, also known at times during his life as Li Xulun, Li Lun, Wu Lun, and Wu Dan, was the fifth and ninth emperor of Tang Dynasty. He was the sons of Emperor Gaozong and Wu Zetian. He was the brother of Emperor Zhongzong. He was the Emperor of Tang Dynasty for two times.