Tan Sitong (10 March 1865 - 28 September 1898), was a well-known Chinese politician, thinker, and reformist in the late Qing dynasty (1644-1911). He was executed at the age of 33 when the Hundred Days' Reform failed in 1898 Tan Sitong was one of the six gentlemen of the Hundred Days' Reform, and occupies an important place in modern Chinese history.