Huang Longshi (黄龍士, a.k.a. Huang Yuetian & Longshi, the Prodigy, 1651/54 - ca. 1700) was a go player in the Kangxi period of the Qing dynasty in China. He became guoshou at age 16, one of the fourteen sages of ancient China by his contemporaries, and subsequently praised as one of the most accomplished go players of all time.
Longshi is known for his contribution to the use of influence and thickness by learning how to force his opponent inefficient or over-concentrated shape. This has led some commentators to suggest a parallel development of tewari analysis alongside Honinbo Dosaku, though at a less rigorous level. He was a very strong fighter -- mastering the art of amarigatachi and building territory while attacking on a global scale. His games are also noted for their frequent inclusion of myoshus (excellent moves) and surprising tesujis.
Longshi was responsible for many famous games, the most famous being the Games of Blood and Tears against Xu Xingyou. Other notable games are against friend and rival Zhou Donghou; and against the old master Sheng Dayou.
Famous book publisher Deng Yuanhui said:
Longshi used his mind most meticulously. He sought to enter the deepest apertures. When it became a critical matter of life and death, and while the crowd were already helpless and at their wits' end, he was expertly exerting a subtle influence, and seeing more and more skilfull ideas and magical effects; the air would suddenly change... and from death he would re-enter life.
Longshi is like a heavenly spirit turned human. He is absolutely not of this world.
Essay on Huang Longshi and his contemporaries by John Fairbairn: http://web.archive.org/web/20110608015235/http://www.msoworld.com/mindzine/news/orient/go/history/longshi.html
Zengarden: Countsheep, a very strong Chinese amateur, has produced a fantastic and instructive commentary on the game Huang Longshi v Jiang Tianyuan (1680) on Youtube, as part of his "Greatest games ever played" series. This wonderful game is a lesson on how to use influence: see http://www.gocommentary.com/free-videos/the-greatest-games-ever-played-04-huang-longshi-vs-jiang-tianyuan.html Very highly recommended.
There are also 28 deeply commented games available in a Chinese book by a contemporary weiqi master called Xue Zhi Cheng. I managed to obtain a copy from a contact in Shanghai and the book is very impressive. The book was published in 2007 by China Metrology Publishing House, Beijing. (I believe the author can be contacted at firstname.lastname@example.org.)
Xue Zhi Cheng has also done a commentary on selected games of Huang Longshi's pupil Xu Xingyou.
There is also a very good two volume games collection by Ma Zheng: Qi sheng Huang Longshi quan pu / Ma Zheng bian zhu 棋圣黄龙士全谱 / 马诤编著 by Ma, Zheng 马诤 Beijing Shi : Ren min ti yu chu ban she, 2009 北京市 : 人民体育出版社, 2009
This two volume survey, part of a series on old Chinese masters, includes "games of Blood and Tears" and other classic Huang Longshi games.
Michael Redmond has published a book in Japanese on Huang Longshi http://www.amazon.co.jp/%E9%BB%84%E9%BE%8D%E5%A3%AB-%E3%83%9E%E3%82%A4%E3%82%B1%E3%83%AB-%E3%83%AC%E3%83%89%E3%83%A2%E3%83%B3%E3%83%89/dp/4860293770/ref=sr_1_4?ie=UTF8&qid=1350078848&sr=8-4
Zengarden This is a Japanese translation (with a lengthy introduction) of Xue Zhi Cheng's 2007 book mentioned above.