His given name is Yun-ch`ang; his familiar one is Guan Yu but also known as Lord Kwan or Kwan the Noble. He had a huge frame, long beard, dark brown face and deep red lips. "He had eyes like a phoenix and fine bushy eyebrows like silkworms. His whole appearance was dignified and awe-inspiring." He swore an oath of blood brothers with Liu Bei and Zhang Fei in the Peach Garden and fought around China to restore the Han family to power. He was general of the Shu and the first of the "Five Tigers" Generals. His reputation as a skilled swordsman earned him the gift of the Red Hare, the finest steed, from Cao Cao. His unswerving loyalty and strength were crucial to Liu Bei's efforts.

Guan Yu was a very wise and fearless general. He became the head of the "Five Tigers" Generals of Shu. He had two sons and one adopted son. His adopted son, Guan Ping, and his other two sons', Guan Xing and Guan Suo joined him in his battles. He first joined Liu Bei along with Zhang Fei and the three became sworn brothers. Together they commanded the volunteer army of 500 to combat the Yellow Turban Rebels.

During the battle of the United Armies attacking Dong Zhou, Dong Zhou's general Hua Xiong was attempting to slaughter all of the generals from the United Armies. No general dared to challenge him. Then at the critical moment Guan Yu stood up, but some of the highly ranked generals did not agree to let him go because at that time Guan Yu only held the rank of an Archer, but Cao Cao managed to persuade them to let Guan Yu go. Guan Yu went to face Hua Xiong and defeated him with just one bout and returned to the United Army's camp with his head in hand. From then on Guan Yu was well known for defeating Hua Xiong. Afterwards he participated in the famous battle known as "Three heroes battle Lu Bu".

After the battle against Cao Cao in Xu Zhou, the three sworn brothers became divided. Guan Yu was protecting Liu Bei's wife with only his small army against Cao Cao's great army without having any knowledge of Liu Bei and Zhang Fei's location. Cao Cao greatly admired Guan Yu for his bravery and loyalty. He sent his general Zhang Liao who was an old friend of Guan Yu's to try to persuade him to join Cao Cao. Guan Yu knew that he could not protect Liu Bei's wife safely because of his small army. So he made three agreements with Cao Cao. The first was that he would only surrender to the Emperor as Cao Cao was still the Prime Minister at that time. The second was that Cao Cao would not harm Liu Bei's wife, and third was once he found out where Liu Bei was, he would go join him. Cao Cao agreed to the first two but didn't agree to the third one, but after listening to his advisors' ideas to get rid of Liu Bei, he decided to agree.

During his time in Cao Cao's camp, Cao Cao presented him with many gifts, but Guan Yu returned them all when he left to rejoin Liu Bei. Then Cao Cao gave him a war vest, but Guan Yu wore the new vest under his old one which Liu Bei gave him. Cao Cao was furious at that time and sent Zhang Liao to persuade him to forget about Liu Bei. After their conversation Zhang Liao told Cao Cao that if Liu Bei ever died, Guan Yu would also suicide to follow his "Peach Garden" oath, but he would not leave Cao Cao until he did something in return.

A short time later, Yuan Shao ordered one of his top generals Yan Liang to command his troops to attack Cao Cao. Yan Liang was a very fierce warrior, none of Cao Cao's available generals could defeat him. Cao Cao quickly sent a letter informing Guan Yu to go to the battlefield. Guan Yu easily defeated Yan Liang. In Yuan Shao's capital, the news arrived stating that Guan Yu had defeated Yan Liang. Liu Bei joined Yuan Shao after he became separated from Guan Yu and Zhang Fei. Yuan Shao believed Liu Bei to be Cao Cao's infiltrator so he ordered Liu Bei to be executed. However, Liu Bei was successful in persuading Yuan Shao that it might be Cao Cao's scheme to use someone that looks like Guan Yu to kill Yan Liang to sow discord between Liu Bei and Yuan Shao.

Then Wen Chou, another of Yuan Shao's top generals and sworn brother to Yan Liang was ordered to attack Cao Cao with Liu Bei's help. Again Cao Cao had to use Guan Yu in order to defeat Wen Chou. Wen Chou's army quickly retreated, but Liu Bei managed to catch a glimpse Guan Yu before retreating. After confirming Guan Yu's involvement, Yuan Shao threatened Liu Bei again, but Liu Bei assured Yuan Shao that if Guan Yu was involved, he could persuade Guan Yu to join them. Yuan Shao was overjoyed upon hearing this.

After receiving Liu Bei's letter, Guan Yu quickly informed Liu Bei's wife and they set out to rejoin Liu Bei. Cao Cao heard the news that Guan Yu was leaving and went to bid him farewell at a bridge. Cao Cao respected him so much that he decided to let him go. Guan Yu continued his journey and ran into trouble at the first fort he reached. The commanding general did not want to let him through because Guan Yu did not have a pass from Cao Cao. So Guan Yu was forced to kill him. He passed through a total of five forts and killed six generals without resting. He became well known from that incident, which became known as "Passing five obstacles, killing six generals".

Years passed and Guan Yu was in charge of defending an important territory, Jing Zhou. Cao Cao and Sun Quan allied and launched a joint invasion attacking the territory which Guan Yu had been defending. Guan Yu was not able to defend that place and was captured by Sun Quan. He was then executed by Sun Quan in the year 219 AD. He was fifty-eight.