Water Margin is one of the earliest Chinese novels written in vernacular Mandarin and is attributed to Shi Nai'an. It is also translated as Outlaws of the Marsh and All Men Are Brothers.

The tragic story, set in Northern Song dynasty (around 1120), tells of how a group of 108 outlaws gather at Mount Liang (or Liangshan Marsh) to rebel against the government. Later they are granted amnesty and enlisted by the government to resist the nomadic conquest of the Liao dynasty and other rebels.

While the book's authorship is attributed to Shi Nai'an (1296–1372), there were references laid out in the book that did not exist until the Jiajing reign (1521-1567) of Ming dynasty, sparking a long-lasting academic debate on when it was actually written and which historical events the author had witnessed that inspired him to write the book.

It is considered one of the Four Great Classical Novels of Chinese literature. It has introduced readers to many of the best-known characters in Chinese literature, such as Wu Song, Lin Chong, Pan Jinlian, Song Jiang and Lu Zhishen.

"These seduction cases are the hardest of all. There are five conditions that have to be met before you can succeed. First, you have to be as handsome as Pan An. Second, you need a tool as big as a donkey's. Third, you must be as rich as Deng Tong. Fourth, you must be as forbearing as a needle plying through cotton wool. Fifth, you've got to spend time. It can be done only if you meet these five requirements." "Frankly, I think I do. First, while I'm far from a Pan An, I still can get by. Second, I've had a big cock since childhood."

— An excerpt from the novel with English translation by Sidney Shapiro.