X-5 (엑스파이브) was a Korean pop 5-member boy group that debuted in 2011 under Open World Entertainment. In mid-2012, the group left Open World Entertainment and leader Ghun enlisted into mandatory military service on December 4th. In February 2013, Taefung, Haewon and Sulhu joined a new group called Lu:kus, confirming that the group disbanded.
- [2011.12.09] Dangerous
- [2011.04.22] Xenos
-  MBC Miss Ripley (Ep. 3 Cameo)
- Known as the "tall idol" group, with the shortest member at 183cm
- All members except Haewon, have been trained in martial arts