Monsta X (Hangul: 몬스타엑스; often stylized as MONSTA X) is a South Korean boy group formed by Starship Entertainment through the survival show NO.MERCY on Mnet in 2015. The group is composed of seven members. Jooheon has also been a participant of Season 4 of South Korean TV series Show Me The Money.
The group was formed as the result of a TV program called No Mercy on Mnet, which began running in December 2014. A single released during No Mercy was "0 (Young)," on February 4, 2015 starring Giriboy, Mad Clown, and Jooyoung along with Jooheon, Kihyun, Wonho, Seokwon, and I.M. "Interstellar" was a single released on February 11, 2015 with Jooheon, Hyungwon, and I.M, featuring Yella Diamond.. "Hieut" was a single released on February 26, 2015 starring Nochang, Vasco, and Junggigo along Shownu, Minhyuk, Hyungwon, Yoonho and #Gun. Monsta X signed an endorsement deal with apparel brand Litmus before debut.
Source : wikipedia