Sun Tzu or Sun Zi(孙子) is traditionally believed to be the author of The Art of War, an influential ancient Chinese book on military strategy considered to be a prime example of Taoist strategy. Sun has had a significant impact on Chinese and Asian history and culture, both as an author of the Art of War and as a legendary figure. During the 19th and 20th centuries, Sun's The Art of War grew in popularity and saw practical use in Western society, and his work has continued to influence both Asian and Western culture and politics.

Historians have questioned whether or not Sun was an authentic historical figure. Traditional accounts place him in the Spring and Autumn Period of China (722–481 BCE) as a heroic general of the King of Wu who lived c. 544—496 BCE. Scholars accepting his historicity place his supposed writing The Art of War in the Warring States Period (476–221 BCE), based on the descriptions of warfare in the text. Traditional accounts state that his descendant, Sun Bin, also wrote a master treatise on military tactics.

Historians have questioned whether or not Sun was a real historical figure. According to traditional sources, such as the 2nd century BCE biography written by Sima Qian, Sun was born in Qi (now Shandong Province) during the Spring and Autumn Period of China (722–481 BCE). His real family name is Tian, but the last name of Sun was given by King of Qi State to his family when his grandfather, a general for Qi, won a big battle. When Sun Tzu was young, his family was having trouble with some royal families, and he moved to Wu state and became a heroic general for the king of Wu, Helü. His victories then inspired him to write The Art of War. Historians place the writing of The Art of War in the Warring States Period (476–221 BCE), based on its description of warfare. The period was a time of constant war among seven nations (Zhao, Qi, Qin, Chu, Han, Wei and Yan) seeking to control all of China.

The king of Wu tested Sun's skills by commanding him to train a harem of 360 concubines into soldiers. Sun divided them into two companies, appointing the two concubines most favored by the king as the company commanders. When Sun first ordered the concubines to face right, they giggled. In response, Sun said that the general, in this case himself, was responsible for ensuring that soldiers understood the commands given to them. Then, he reiterated the command, and again the concubines giggled. Sun then ordered the execution of the king's two favored concubines, to the king's protests. He explained that if the general's soldiers understood their commands but did not obey, it was the fault of the officers. Sun also said that once a general was appointed, it was their duty to carry out their mission, even if the king protested. After both concubines were killed, new officers were chosen to replace them. Afterward, both companies performed their maneuvers flawlessly. Sima's biography claims that Sun later proved on the battlefield that his theories were effective, that he had a successful military career, and that he wrote The Art of War based on his tested expertise. His descendant, Sun Bin, also became a famous scholar of the military arts.

Scholars have expressed doubt in Sun's historicity and the traditional dating of The Art of War. The skepticism is fueled by factors that include historical inaccuracies and anachronisms in the text, as well as the unlikelihood of the execution of the king's favorite concubines. Increasing skepticism, which sometimes cause scholars to completely deny the existence of a historical figure named Sun Wu (Sun Tzu), has lead to acrimonious debate between skeptics and traditionalists, especially in China. Attribution of The Art of War's authorship varies among scholars, and have included people and movements including Sun; Chu scholar Wu Zixu; an unknown author; a school of thought in Qi or Wu; and Sun Bin.

Traditionalists attribute the authorship of The Art of War to the historical figure Sun Wu, who is chronicled in the Records of the Grand Historian and the Spring and Autumn Annals. He was reputedly active in the early 6th century BCE, beginning c. 512 BCE. The appearance of features from The Art of War in other historical texts is considered to be proof of his historicity and authorship. Certain strategic concepts, such as terrain classification, are attributed to Sun Tzu. Their use in other works, such as by the compilers of The Methods of the Sima, is considered proof of Sun Tzu's historical priority.

Scholars that identify issues with the traditionalist view point to anachronisms in The Art of War that include terms, technology, philosophical ideas, events, and military techniques. There is a disparity between the large scale wars and sophisticated techniques detailed in the text, and the more primitive small scale battles that predominated the 6th century BCE. There is also a lack of early contemporary evidence supporting the centuries-later accounts of Sun. For example, there is no corroborating support for his role in the wars between Wu and Yue in the Zuo Zhuan, which is considered the authoritative record of the period. Regardless of Sun's historicity and the actual authorship of The Art of War, the figure of Sun and his traditionally attributed work have been influential.

Sun's The Art of War has influenced many notable figures. Traditional histories recount that the first emperor of a unified China, Qin Shi Huang, considered the book invaluable in ending the Age of Warring States. Japan was introduced to The Art of War c. 760 CE, and the book quickly became popular among Japan's generals. The publication also significantly influenced the unification of Japan. Mastery of its teachings was considered a mark of respect among the samurai, and its teachings were both exhorted and exemplified by influential samurai such as Oda Nobunaga, Toyotomi Hideyoshi, and Tokugawa Ieyasu. Historians popularly recount how French emperor Napoleon studied Sun's military writings and used them to successfully wage war against the rest of Europe. The emperor's disregard for central principles such as attentiveness to temporal conditions is largely credited for his eventual defeat in Russia. Admiral of the Fleet Tōgō Heihachirō, who led Japan's forces to victory against Russia in the Russo-Japanese War, was a famous disciple of The Art of War's teachings.

Communist Chinese leader Mao Zedong partially credited his defeat of Chiang Kai-shek and the Kuomintang in 1949 to The Art of War. The work strongly influenced Mao's writings about guerrilla warfare, which further influenced communist insurgencies around the world. During the Gulf War in the 1990s, General Norman Schwarzkopf, Jr. practiced Sun's principles of deception, speed, and attacking the enemy's weakness. Mark McNeilly writes in Sun Tzu and the Art of Modern Warfare that a modern interpretation of Sun and his importance throughout Chinese history is critical in understanding China's push to becoming a superpower in the 21st century. Modern Chinese scholars explicitly rely on historical strategic lessons and The Art of War in developing their theories, seeing a direct relationship between their modern struggles and those of China in Sun's time. There is a great perceived value in Sun's teachings and other traditional Chinese writers, which are used regularly in developing the strategies of the Chinese state and its leaders.