Zhang Heng, the son of Zhang Daoling 张衡

Zhang Heng (?–179), the son of Zhang Daoling, was the second Celestial Master of Taoism, with the courtesy name Lingzhen. He inherited the Taoist teachings in the second year of the Yongshou era of the Han Dynasty (156). According to records, after Zhang Daoling attained Taoism, Zhang Heng "practiced his Tao".

In his youth, Zhang Heng was erudite. He lived in seclusion and refused to enter officialdom, yet he had a great reputation. He dedicated himself to pursuing the Tao and paid no attention to an official career. Despite several recruitments by the imperial court at that time, he declined all of them. After inheriting the teachings, he resided in Yangping Mountain (present-day Peng County, Sichuan) and taught his disciples using Taoist scriptures and talismans.

In the first month of the second year of the Guanghe era (179), Zhang Heng passed down the ancestral seal and sword to his son Zhang Lu, and attained Taoism together with his wife Lady Lu in Yangping Mountain. In the first year of the Zhida era of the Yuan Dynasty (1308), he was conferred the title of "Orthodox Successor Master, Supreme Purity Preacher of Wonderful Tao, True Lord".