Xu Gan (Chinese: 徐幹, pinyin Xú Gàn, 171–218), courtesy name Weichang ( 偉長), was a Chinese philosopher and poet of the late Eastern Han dynasty. 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).