In Taoism myth
From the idea of Taoism, Guangchengzi was the avatar of Taishang Laojun (also named Daode Tianzun) during the period of Yellow Emperor in ancient Chinese history. According to Zhuangzi's recording, Guangchengzi lived in Kongtong Mountains, the Yellow Emperor visited him there for his teaching. Guangchengzi gave the Yellow Emperor several books that talked about the moral, natural, and philosophical issues, which helped the Yellow Emperor create the early Chinese civilization. It is said that Guangchengzi had a long life of 1200 years. There is another saying that Guangchengzi was the avatar of Dao,[disambiguation needed] who appeared in the human world three times – the first time as Guangchengzi during the Yellow Emperor time; second as Laozi during the Spring and Autumn period; and third time as Zhang Daoling in the Han Dyansty.
From Fengshen Yanyi's idea
From the novel of Fengshen Yanyi, Guangchengzi is the student of Yuanshi Tianzu, who is the co-founder of Branch Chan of Taoism. Guangchengzi ranked the first of the Twelve Golden Xian (十二上仙) along with Yuanshi Tianzun's other eleven students: Chijingzi, Yuding Zhenren, Taiyi Zhenren, Huanglong Zhenren, Wenshu Guangfa Tianzun (also known as Manjusri), Puxian Zhenren (also known as Samantabhadra), Cihang Daoren (also known as Guanyin), Lingbao Dafashi, Jvliusun (also known as Kakusandha Buddha), Daoxing Tianzun, and Qingxv Daode Tianzun. All those twelve Xians and their students together with Jiang Ziya made great contributions to help King Wu of Zhou conquered King Zhou of Shang (who got the support of the Branch Jie).
On his visit to Jin'ao Island to see Tongtian Jiaozhu--the founder of Branch Jie, Guangchengzi killed Tongtian Jiaozhu's student Jinguang Shengmu by mistake, which made the other people from Branch Jie very angry. Guangchengzi was able to leave that island after that, but the direct war between Branch Jie and Branch Chan began. That huge war had lasted for a long time, lots of gods and Xians got injured or even killed in the war. And at last the Branch Chan beat Branch Jie.
Weapons of Guangchengzi
Guangchengzi has three weapons: Fantian Yin, Luohun Bell, and Female-Male Double Sword. Fantian Yin is the Guangchengzi's best weapon, it is said to be a huge seal, which made by Guangchengzi's teacher Yuanshi Tianzun and then passed to Guangchengzi, Fantian Yin is driven by magic, it kills people by hitting the forehead; Luohun Bell is a bell that makes the sound to interrupt enemies' soul; Female-Male Double Sword is a pair of swords, those swords were believed to have genders, one is female and one is male, and Guangchengzi was then being considered as the master of Chinese sword culture.
He has sacrificed many upon many of years to solitude and has emerged as an immortal. Originally, this superior man had been within the Peach Stream Cave of Mount Nine Elves. After he, along with his fellow immortal by the name of Chijingzi had been passing by King Zhou's capital, Zhaoge, two very large beams of red light from heaven had impeded Guangchengzi's path. After Guangchengzi personally saw beneath him the unfortunate events taking place - the near execution of both the crown princes Yin Jiao and Yin Hong- Guangchengzi would say that it would be best to create a very large tornado over the capital and use the confusion to steal both of the princes – as to ensure the creation of the new dynasty. Guangchengzi took Yin Jiao as his student, and Chijingzi took Yin Hong as student. After several decades of studying, Yin Hong was strong enough to do some contributions to the world, thus Guangchengzi gave him the Fantian Yin along with some other weapons and asked Yin Jiao to help Jiang Ziya and King Wu of Zhou. However, on Yin Jiao's way to the camp of King Wu's army, he met a bad person called Shen Gong Bao, who persuaded Yin Jiao should help his father King Zhou to fight against King Wu, and protect the country of Shang. As a youth who did not have much social experiences, Yin Jiao accepted Shen Gong Bao's suggestion and started to fighting against King Wu's army, which totally against his teacher Guangchengzi. And at last, Guangchengzi killed Yin Jiao.
- Investiture of the Gods chapter 9 pages 107-108