Zhang Xu, courtesy name: Bogao 伯高), was a Chinese calligrapher of the Tang Dynasty. A native of Suzhou, he became an official during the reign of Emperor Xuanzong of Tang. Zhang was known as one of the Eight Immortals of the Wine Cup. Legend has it that whenever he was drunk, he would use his hair as brush to perform his art, and upon his waking up, he would be amazed by the quality of those works but failed to produce them again in his sober state. Wikipedia
The definitive Wikipedia entry for Zhang Xu. Wikipedia is the biggest multilingual free-content encyclopedia on the Internet. en.wikipedia.org/wiki/Zhang_Xu_%28calligrapher%29
