Wu Sansi (died August 7, 707[1]), known posthumously as Prince Xuan of Liang (梁宣王), was a Chinese prince and politician of the Tang and Wu Zhou dynasties. Wu Sansi served as a chancellor and imperial prince during the reign of his aunt, Empress Wu Zetian of Zhou, and was again a powerful chancellor during the second reign of Empress Wu's son, Emperor Zhongzong of Tang. He was aided in navigating the fraught period that followed Emperor Zhongzong's restoration by successive affairs with the influential consort Shangguan Wan'er and the powerful Empress Wei. Although he amassed significant authority and enjoyed the trust of Emperor Zhongzong, he was killed during an unsuccessful rebellion by the crown princeLi Chongjun in 707.