Seong Hyun Woo (성현우), also known as WOO, is a South Korean singer under GDHG.
Woo was first known for appearing in the hit survival show "Produce 101 Season 2." Following the show's conclusion, he debuted as the leader, lead rapper, and main dancer of the boy group LIMITLESS, using the stage name A.M. Although there were no official announcements, LIMITLESS became inactivite and was eventually presumed to have disbanded.
In February 2021, he made his official solo debut with the digital single "I Still Love You" under his own company called GDHG, using the stage name WOO.