刘瑾（1451年2月28日－1510年8月25日），陕西兴平人。中国明代中期，明武宗时期的重要宦官。

据史书所记，刘瑾本姓谈，景泰年间自宫，并成为刘太监外间的手下，并改刘姓。成化年间入宫。弘治年间执掌茂陵司香，其后调往东宫。由于经常在太子面前演戏，深得太子所宠爱。但亦有小说家称传闻刘瑾在弘治年间在宫内已有实权，并设有豹房，把不听话的太子关在豹房内恐吓。由于明武宗在刘瑾死后的生活荒淫无道，与其父明孝宗大为不同，不少小说家穿凿附会，并借用刘瑾这豹房的传言，借以编造故事，并指他其实并非真正的太监，及经常淫乱宫庭云云。

Liú Jĭn (simplified Chinese:刘瑾; traditional Chinese:劉瑾) ( 28 February, 1451– 25 August, 1510 ) was a well-known Chinese eunuch during the reign of the Chinese Ming Dynasty Zhengde Emperor (r. 24 January 1506 – 20 April, 1521). Liu was famous for being one of the most corrupt officials in Chinese history and the emperor in all but name for some time. He was the leader of the "Eight Tigers", a powerful group of eunuchs who controlled the imperial court. Liu Chin is from the area of Xingping, a county in Shaanxi province, approximately 30 miles west of Xian prefecture. A son of Tan (談) lineage, when he was made a eunuch under the aegis of a eunuch official named Liu, he appropriated that surname.