Xu Gan (171–218), courtesy nameWeichang, was a philosopher and poet of the late Eastern Han dynasty of China. He was also one of the "Seven Scholars of Jian'an". He is best known in the West for his discourse on the relationship between the names and actualities, preserved in his treatise Zhonglun (中論).
Born in Ju County, Beihai Commandery (east of present-day Lechang, Shandong), Xu Gan developed a reputation for good memory and diligent studies as a youth. Around 189, Xu Gan left his residence in Linzi and went into hiding on the Jiaodong peninsula.