Zhang Guolao; also known as Zhang Guo; is a historical figure and one of the Eight Immortals. He is said to have been born during the middle or end of the 7th century CE; during the Tang Dynasty; and was a Taoist 'fangshi' (occultist-alchemist) who lived as a hermit on Zhongtiao Mountain. Zhang was portrayed with a strong love for wine and winemaking; and was a master of 'qigong' (life energy cultivation); able to survive for days without food and only a few sips of wine.

Zhang Guolao claimed to be several hundred years old by the time Empress Wu Zetian came to power. He traveled often on the back of a white donkey or mule; which he could fold away and place in his pocket after he was done traveling. He constantly declined invitations to the courts of the Tang Dynasty emperors; only agreeing to leave his hermitage when Wu Zetian asked. However; he died just as he reached the gates of the Temple of the Jealous Woman; his body swiftly decomposing. He was soon seen alive and well on Zhongtiao Mountain however.

Zhang Guolao was considered the most eccentric of the Eight Immortals; known as an entertainer and for his various whimsical acts.