Chuang Chou tzu, 399bce to 295bce. Also spelled "Zhuangzi." Also known as the "Butterfly philosopher."

Chuang Chou is the author of a book referred to simply as the Chuang tzu, which is considered one of the two core books of Taoism (the other being the Tao Te Ching). Chuang took the basic Taoist philosophy of Lao tzu and developed it into a way of life; in many ways, it can be said that Chuang tzu had more of an influence on Taoism as a movement than did the mysterious Lao tzu himself. Chuang developed te as an ethical concept, theretofore only primitively understood, and linked te more closely with tao.

Little is known about Chuang Chou the man. Some sense of his spirit and sense of humour can be seen in his writings. Some was also recorded by his contemporaries, but little of this record remains intact today, almost 2,300 years later. It is known that later in his life, Chuang was offered a high public position because of his reputation as a wise man, which he refused.

Today, Chuang tzu is sometimes compared to Friedrich Nietzsche, a comparison that puzzles those familiar with only one of the two men. However, the points of comparison are plentiful, not only in their style, but also in the content of their doctrines. Both men enjoyed satirising the revered figures of their time — Nietzsche mocked Socrates and Jesus Christ, whereas Chuang tzu used Confucius as his foil. Both men stressed the role of self-invention as an ethical process. Both men also promoted the ideal of a man who swelled with such natural power that he could not be harmed, for whom harming would be more of a waste than letting people harm him unretributed. Chuang tzu's te is comparable to Nietzsche's conception of power, and in many ways the doctrine of the Tao is analogous to that of the Will to Power.

The book Chuang tzu consists of roughly two parts, called the "Inner Chapters" and the "Outer Chapters." It is commonly held that Chuang tzu himself only wrote the Inner Chapters (the first seven), with the Outer Chapters having been anonymous additions, supplements, and commentary from various followers through the ages.