NCT 127 is the first fixed and second overall sub-unit of the South Korean boy band NCT, formed and managed by SM Entertainment. They originally debuted on July 7, 2016, with their debut extended play NCT #127, with an original lineup of seven members: Taeil, Taeyong, Yuta, Jaehyun, Winwin, Mark, and Haechan. Doyoung and Johnny joined the unit in December 2016, ahead of their second EP Limitless, while Jungwoo, the final member, was introduced in September 2018 ahead of their first studio album Regular-Irregular. They are known for their experimental hip hop-based music, which they refer to as "neo music", as well as their vocal and rap abilities, choreographies, and performances.

Lee Dong-hyuck, known professionally as Haechan (해찬), is a South Korean singer. He is a member of South Korean boy band NCT and sub-units NCT 127 and NCT Dream.