Yà Ân Namgà Ân (æ·µç·建, ì°ë¨건) (635 ~ ?) was the second son of the Goguryeo military leader and dictator Yà Ân Kaesomun (Unknown-666), and third Tae Mangniji of Goguryeo during the reign of Goguryeo's last ruler, King Bojang.
Following the death of his father in 666, Namgà Ân became embroiled in a power struggle with his elder brother Yà Ân Namsaeng. Namgà Ân and his younger brother Namsan staged a coup against their older brother when he was inspecting all of the fortresses of Goguryeo to prepare for war against the Tang. Namgà Ân and Namsan's coup forced Namsaeng to surrender to the Tang, and ultimately led to the destruction of Goguryeo. Namgà Ân appointed himself Tae Mangniji (ëÂÂë§Â리ì§Â, 大è«é¢æ¯) and seized control of the government.
During Tang's subsequent invasion of 668, Namgà Ân led armed resistance to the Chinese forces near the Amnok River and continued to resist the Tang forces all the way to Pyongyang. With Goguryeo's defeat, Namgà Ân found himself a prisoner of war and was transported to China and later banished to Qianzhou (é»Âå·Â), in what is today China's Sichuan province, where he apparently died. The tomb steles of Namgà Ân's siblings Namsaeng and Namsan are extant but offer no particulars regarding the life of Namgà Ân. Had Namgà Ân and his brothers united to work together, Goguryeo would have lasted for a much longer period of time, but Silla sent their spies into the brothers' inner circle of advisors to try and create a rift between the brothers.