Zengzi was a Chinese philosopher and writer of the fifth century BCE, a citizen of the state of Lu.

Born around 505 BCE, Zengzi died sometime in the mid-430s BCE, with sources placing his death at 437, 436, or 434 BCE. The range of dates attached to his life reflects the difficulties of recovering precise biographical detail from ancient records transmitted and copied across many centuries. The authorized Library of Congress name authority gives his dates as 505 BCE to 437 or 436 BCE, while other sources extend the range slightly in either direction.

Zengzi held citizenship of Lu and worked in the Chinese language as both a philosopher and a writer. These two roles overlapped naturally in his era, and his identity in the historical record rests on both. The uncertainty that attaches to his exact dates does not obscure the basic shape of his life: a figure active in philosophical and written work during the fifth century BCE in ancient China.

The facts that define Zengzi in the available record are spare but consistent. He was a male philosopher and writer, born in China around 505 BCE, who died in the first half of the fourth century BCE. His citizenship was that of Lu, and Chinese was the language in which he worked. These coordinates — time, place, citizenship, and practice — constitute the anchored outline of a life given to philosophy and writing.