Liu Xu (; 888–947), courtesy name Yaoyuan (), formally the Duke of Qiao (), was a Chinese historian and politician of the Chinese Five Dynasties and Ten Kingdoms Period states Later Tang and Later Jin, serving as a chancellor during both of those short-lived dynasties. He was the lead editor of the Old Book of Tang, one of the official histories of the preceding Tang Dynasty, completed during Later Jin, although most of the work was probably completed during the term of his predecessor Zhao Ying. Background Liu Xu was born in 887, during the reign of Emperor Xizong of Tang. His family was from Zhuo Prefecture (涿州, in modern Baoding, Hebei). His grandfather Liu Cheng () and father Liu Yin () both served as officers at You Prefecture (幽州, in modern Beijing). It was said that in his youth, Liu Xu was known for his handsome appearance and his literary abilities, and both his older brother Liu Xuan (rendered 劉晅 in the History of the Five Dynasties and 劉暄 in the New History of the Five Dynasties) and younger brother Liu Hao () were known in their home territory. Sometime during the Tianyou era (904-907), there was a time when forces of the Khitan captured Zhuo, and Liu Xu was captured and taken to Xin Prefecture (新州, in modern Zhangjiakou, Hebei), but he escaped his Khitan captors. He later took up residence at Mount Daning (), living with Lü Mengqi () (later a Later Tang official as well) and Zhang Lin (), spending the time reciting and writing poems. At one point, Wang Chuzhi, then ruling Yiwu Circuit (義武, headquartered in modern Baoding) as its military governor (Jiedushi), commissioned his adoptive son Wang Du as the prefect of Yi Prefecture (易州, in modern Baoding). Wang Du invited Liu to serve on his staff as his secretary in military matters. Later, after Wang Du completed his term as the prefect of Yi — probably at the time that Wang Chuzhi commissioned Wang Du as the deputy military governor of Yiwu — Liu requested to leave governmental service. Instead, Wang Du invited him to go to Yiwu's capital Zhongshan () with Wang Du. At that time, Liu Xu's older brother Liu Xuan also arrived from Zhuo, and Wang Du recommended both of them to his father Wang Chuzhi. Wang Chuzhi commissioned Liu Xu as his secretary in headquarter matters, and shortly