Fa Zheng (Chinese: 法正) is a character in the 14th-century Chinese classic novel Romance of the Three Kingdoms by the late Luo Guanzhong, and its multiple adaptations. He is a vassal who first worked for Liu Zhang. After Liu Bei invaded the province, he served his new lord as a master strategist. He was greatly favored by Liu Bei and was considered one of his closest advisors. He also appears as a playable character in the Dynasty Warriors series.
On the recommendation of his friend Zhang Song, Fa Zheng was sent by Liu Zhang to Jing Province to enter into an alliance with Liu Bei. From then on, he began planning with Zhang Song and Meng Da to hand over Yi Province to Liu Bei. He even tried to get Liu Zhang's assassination approved by Liu Bei, but he rejected the idea. Fa Zheng is under the request of Liu Zhang and made sure to enjoyed Liu Bei's objects. With his knowledge of the topography of the region, he was very helpful when Liu Bei conquered Yi Province and wrote a letter in which he urged Liu Zhang to surrender. Liu Zhang abandoned the struggle and surrendered his land to Liu Bei. Although Fa Zheng was known to administer harshly and aggressively, he advised Zhuge Liang to lighten the criminal laws, which was refused.
Later on, Fa Zheng proposed an attack on Hanzhong and by his schemes, he helped Huang Zhong to defeated Xiahou Yuan during the battle of Mount Dingjun. He allowed Liu Bei to take possession of Hanzhong. At some point, Liu Bei entered the Mount Dingjun camp and confronted Xiahou Yuan. Meanwhile, Xiahou Yuan was stationed at Zouma Valley and Zhang He was stationed at Guangshi, Fa Zheng took the sound of the east and hit the west, Liu Bei divided the more than 10,000 soldiers into the 10th teams and attacked Guangshi in round of the night. Zhang He beat the pro-arms and did not lose his stronghold, but could not resist the turn of Liu Bei's forces and asked Xiahou Yuan for reinforcements. Xiahou Yuan will split the soldiers to support Zhang He and continue to stick to the southline.
However, after this, Liu Bei sent his troops to attack on Zouma Valley and set fire to the defensive antlers in front of the Wei armies positions, Xiahou Yuan personally led four hundred sergeants to campfire and repair antlers. In some case, Fa Zheng looking at the right time and see Xiahou Yuan was at a disadvantage. He proposed to attack Xiahou Yuan with his forces, Liu Bei was forced to attacked from the rear by Huang Zhong on the mountain. After Xiahou Yuan's death, Zhao Yun responded to Huang Zhong and saved him, Wei forces was already defeated. Before the establishment of Shu Han, he convinced Liu Bei to marry Wu Yi's younger sister, Empress Mu. After Cao Cao's forces were totally repulsed from Hanzhong, Fa Zheng died of illness and Liu Bei cried for days.
- Fa Zheng is one of the minor characters in the Knights of Valour series.