Taoist who organized many of the ceremonies and rites of the Taoist cult and reformulated its theology. His influence was such that he had Taoism (Daoism) established as the official state religion of the Northern Wei dynasty (386–534/535); this act, however, embroiled Taoism in long and often bloody factional political struggles.

K'ou apparently began his career as a Taoist physician and hygienist. But in 415 he had a vision: a spirit appeared before him and told him that since the death of Chang Ling (34?–156), the great founder of the Taoist Church, the cult had been perverted by false doctrines. K'ou was awarded Chang Ling's old title of t'ien-shih (“celestial master”) and was charged in the vision with eliminating excesses in Taoist rituals. Accordingly, K'ou began to attempt to curb the orgiastic practices and mercenary spirit that had become associated with Taoist rites and to place greater emphasis on hygienic ritual and good works.

K'ou gained many adherents and, by making Taoism into a more orthodox doctrine, attracted the attention of Emperor T'ai-wu ti (reigned 423–452). In 423 K'ou had the title of t'ien-shih conferred upon himself by Imperial decree, thereby establishing the “Taoist papacy”: the title was passed to the church's leader from generation to generation in an unbroken line. By conspiring with certain court officials, K'ou was able to have Buddhism, Taoism's chief competitor, proscribed from the realm and all its practitioners subjected to a bloody persecution. Taoism then became the official religion of the empire.

But K'ou's efforts were only temporarily effective: Buddhism soon returned to China, stronger than ever. Moreover, because orgiastic Taoist rites were still noted as late as the T'ang dynasty (618–907), many observers view his reforms as transitory.