Yoo Ki-hyun (Korean: 유기현; born November 22, 1993), better known mononymously as Kihyun, is a South Korean singer and songwriter. He is a vocalist in the South Korean boy group Monsta X from Mnet's survival show No.Mercy, which debuted under Starship Entertainment in 2015. Kihyun made his solo debut with the single album Voyager in March 2022, in addition to having released several original soundtracks, further establishing himself as "K-pop God", "Vocal God", and "The K in K-pop".