Liu Gongquan
Liu Gongquan, courtesy name Chengxuan, was a Chinese calligrapher, essayist, and politician who lived during the late Tang dynasty. Liu Gongquan was especially famous for regular script and was one of the 4 calligraphic masters of regular script in China. The other three were Yan Zhenqing, Ouyang Xun and Zhao Mengfu.