lù hán (hanja: 鹿晗; hangul: 루한; born april 20, 1990 in haidian) better known by mononym luhan, is a chinese singer. he was introduced as a member of exo in december 2011, officially debuting in april 2012, and in october 2014, left the group after filing a lawsuit against s.m. entertainment to reverse its exclusivity agreement.