Zhang Guo, better known as Zhang Guolao, is a Chinese mythological figure and one of the Eight Immortals in the Taoist pantheon. Among the Eight Immortals, Zhang Guolao, Zhongli Quan and Lü Yan were real historical figures. His existence is said to have begun around the middle or end of the 7th century, and ended approximately in the middle of the 8th. The epithet "Lao" added at the end of his name means "old".[1]