Laozi (also Lao-Tzu /ˈlaʊˈdzʌ/ or Lao-Tze, Chinese: 老子; pinyin: Lǎozǐ, lit. "Old Master") was an ancient Chinese philosopher and writer. He is known as the reputed author of the Tao Te Ching and the founder of philosophical Taoism, and as a deity in religious Taoism and traditional Chinese religions.

Although a legendary figure, Laozi is usually dated to around the 6th century BCE and reckoned a contemporary of Confucius, but some historians contend that he actually lived during the Warring States period of the 5th or 4th century BCE. A central figure in Chinese culture, Laozi is claimed by both the emperors of the Tang dynasty and modern people of the Li surname as a founder of their lineage. Laozi's work has been embraced by various anti-authoritarian movements as well as Chinese legalism.