Fa Zheng (176–220), style name Xiaozhi (孝直), was an advisor to the warlord Liu Bei during the late Han Dynasty period of Chinese history.
Originally, Fa Zheng and his friend Meng Da went to work for Liu Zhang in Yi Province, but Liu Zhang was not a good judge of character and Fa Zheng felt unappreciated. Fa Zheng held the post as Prefect of Xindu, and then became Military Consultant Colonel. Fa Zheng then was defamed by someone else, he felt disparaged. His friend Zhang Song also felt Liu Zhang was not a good leader. With Zhang Song's advice, Fa Zheng became the envoy to Liu Bei to ask him to bring his army into Yi province to defeat Zhang Lu's invading army. Upon talking with Liu Bei, Fa Zheng thought Liu Bei was a wise leader and so he secretly planned to subvert Liu Zhang's territory to give to Liu Bei instead. He then helped with Liu Bei's invasion of the region that would become known as Shu Han.
After the death of Pang Tong, Fa Zheng was arguably the greatest tactician in Shu Han and was the most reliable vassals for Liu Bei. At Liu Bei's invasion of Hanzhong, he acted as military advisor for Liu Bei, then, defeated Cao Cao's army and seized Hanzhong. When he died in 220 at the age of 45 (by East Asian age reckoning) because of an illness, Liu Bei was said to have wept day after day for him and gave him the posthumous rank of "Marquis of Wing"; he was the only person who was given a posthumous marquis rank by Liu Bei. According to Zhuge Liang's opinion, if Fa Zheng was still alive, he would have prevented Liu Bei from attacking Sun Quan in the aftermath of Guan Yu's death, but if Liu Bei had gone anyway, he would not have lost the Battle of Xiaoting.
Read more about Fa Zheng: Appointments and Titles Held