Gu Tan (c. 205–246), courtesy name Zimo, was an official of the state of Eastern Wu during the Three Kingdoms period of China.
Gu Tan became Commandant Who Upholds Righteousness (輔正都尉) and continued playing a supporting role to Sun Deng.
[5] Among his four attendants, Sun Deng favoured and trusted Zhuge Ke and Gu Tan the most, and he regarded them more highly than others such as Fan Shen (范慎), Xie Jing (謝景) and Yang Hui (羊徽).
[9] During the Chiwu era (238–251) of Sun Quan's reign, Gu Tan replaced Zhuge Ke as Left Regional Governor (左節度).
Sun Quan favoured Gu Tan for his talents so much that he awarded him several gifts and had special meetings with him.
[11] Whenever Gu Tan read documents, he could easily spot mistakes simply by browsing through quickly; his subordinates were very impressed with him.
[12] At the time, Xue Zong, who was serving as Master of Writing in the Selection Bureau (選曹尚書; the equivalent of present-day human resources director) in the Wu government, decided to give up his position to Gu Tan.
[13] Around 244, some months after his grandfather's death, Gu Tan was appointed Minister of Ceremonies (太常) in the Wu imperial court.
Sun Ba, knowing that their father favoured him, started fighting with his brother over the position of crown prince.
[23] During an imperial court session, Sun Quan ordered Gu Tan to publicly apologise for the mistake.
When he was in exile, Gu Tan wrote a 20-chapter book, Xin Yan (新言; New Arguments), to express his frustration and lament at his own plight.