South Korean singer-songwriter and actor. He launched his singing career after winning the talent reality show Superstar K in 2009, and made his acting breakthrough in Reply 1997. Since then, he has starred in television series Master's Sun, High School King of Savvy, Hello Monster, Squad 38, Shopping King Louie, The Smile Has Left Your Eyes, Doom At Your Service, Café Minamdang, and Death's Game