Zhang Guolao

Tang-dynasty historical records mention a hermit named Zhang Guo who lived in the Zhongtiao Mountains, was reputed by contemporaries to possess extraordinary longevity, and was summoned more than once to the imperial court by Empress Wu Zetian and later Emperor Xuanzong — invitations he is said to have evaded or accepted only reluctantly, in keeping with the broader hermit-immortal convention of resisting entanglement with worldly power. This historical kernel was elaborated over subsequent centuries into the fuller legend absorbed into the Eight Immortals cycle: an ancient sage of uncertain but vast age, whose signature eccentricity is riding his white donkey facing the animal's tail rather than its head, said to be able to travel enormous distances in a day and, at rest, to fold the donkey flat and store it away like a sheet of paper, unfolding and reviving it with a mouthful of water when travel resumed.

The backward-riding donkey became his defining visual attribute and a folk shorthand for looking at the world differently than convention expects — seeing what lies behind while others look only ahead. He is associated more broadly with longevity and is sometimes invoked in traditional wishes for a long life or, in some regional traditions, for the birth of a son, and appears constantly in Chinese painting and decorative art as one of the most immediately recognisable of the Eight Immortals.