Empress Dowager Xu (徐太后, personal name unknown) (died 926), honored as Empress Dowager Shunsheng (順聖太后) during the reign of her son Wang Yan (né Wang Zongyan), known as Consort Xu with the imperial consort rank Xianfei (徐賢妃) during the reign of her husband Wang Jian, was an empress dowager of the Chinese Five Dynasties and Ten Kingdoms period state Former Shu. She was one of the favorite concubines of Wang Jian, the founder of Former Shu, and through her palace machinations was able to have her son Wang Yan (who was then named Wang Zongyan) made Wang Jian's heir. She was described as beautiful and capable of writing poems, but corrupt. After Former Shu's destruction by Later Tang, she, her son, as well as the rest of the Former Shu imperial family, were executed by Emperor Zhuangzong of Later Tang.
It is not known when the future Empress Dowager Xu was born. It is known that her father was Xu Geng (徐耕), who at one point served as the Tang Dynasty prefect of Mei Prefecture (眉州, in modern Meishan, Sichuan) under Chen Jingxuan the military governor (Jiedushi) of Xichuan Circuit (西川, headquartered in modern Chengdu, Sichuan). Xu Geng was known for being kind and benevolent while serving under Chen, and during Chen's struggles against Wang Jian in 891 as Wang sieged Xichuan's capital Chengdu Municipality, Xu Geng spared many people who considered surrendering to Wang. She was Xu Geng's oldest daughter, and both she and her younger sister (who would also become a concubine to Wang Jian) were very beautiful.
It is not known when the future Empress Dowager Xu became Wang Jian's concubine, but it is known that in 908, shortly after he declared himself the Emperor Shu and created his wife Lady Zhou as his empress, he created both her (who became known as Consort Xu the Greater) and her sister (who became known as Consort Xu the Lesser) as imperial consorts — her title being Xianfei (賢妃) and her sister's title being Defei (德妃). (Consort Xu the Lesser would later receive the title of Shufei.) Both of them became Wang Jian's favorites, and Consort Xu the Greater would bear Wang Jian's youngest of 11 sons, Wang Zongyan the Prince of Zheng, The Consorts Xu formed a close alliance with the eunuch Tang Wenyi (唐文扆) and influenced Wang Jian's policy decisions.