Elder Zhang Guo () is one of the Eight Immortals. He is known as Master Comprehension-of-Profundity (通玄先生 Tōngzhào Xiānshēng).

He lived as an occultist-alchemist (方士) on Mount Tiáo (條山) in Heng Prefecture (恒州 Héngzhōu) during the Tang Dynasty. By the time of Empress Wu (684–705), he claimed to be several hundred years old. He makes liquor from herbs and shrubs as a hobby. Members of the Eight Immortals love to drink his home-made liquor which they believe to have healing or medicinal properties.

Empress Wu summoned him to leave the mountain, so he feigned death. He is the personification of a white bat. He rides a white donkey backward. Emperor Xuanzong attempted to give him an office with the title of Silvery Blue Guanglu Minister (銀青光祿大夫).

He was the most eccentric of the eight immortals, as one can see from the kung fu style that was dedicated to him — which includes moves such as delivering a kick during a backflip , or bending so far back that your shoulders touch the ground!