Koo Jun-yup (Korean: 구준엽; Hanja: 具俊曄; RR: Gu Jun-yeop; born September 11, 1969), also known by his stage name DJ Koo, is a South Korean singer, DJ, music producer, dancer, and songwriter. He is well-known as a member of the legendary K-pop duo CLON. Koo is one of the first-generation Hallyu stars when CLON gained huge popularity internationally, most notably in Taiwan. He is also known as one of South Korea’s most renowned DJs, who has performed at the Ultra Music Festival, Ultra Korea, and World DJ Festival.