Kim Sung-kyun is a South Korean character actor. He began his career in theater in 2003, remaining active as a theater actor in Daehangno from 2004 to 2012. In 2012, he transitioned to film, making his Chungmuro debut in a series of formidable villain roles. These included a gangster in Nameless Gangster: Rules of the Time, a serial killer in The Neighbor, a National Intelligence Service agent in Secretly, Greatly, and a knifeman in Hwayi: A Monster Boy. He ventured into television with supporting roles in Reply 1994 (2013), Reply 1988 (2015–2016), and Moon Lovers: Scarlet Heart Ryeo (2016), as well as leading roles in series D.P. (2021–2023) and Divorce Attorney Shin (2023).