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.

NCT is a South Korean boy band formed and managed by SM Entertainment. Introduced in January 2016, the group currently consists of 26 members divided into six different sub-units: NCT U, NCT 127, NCT Dream, WayV, NCT DoJaeJung, and NCT Wish. They are known for their versatility in music, vocal and rap abilities, and powerful performances, and have been cited as K-pop's "most experimental boy band" due to their concept of having limitless members. As of May 2023, NCT has recorded more than 32 million album sales across all sub-units, making them the best-selling act under SM Entertainment and one of the best-selling K-pop artists of all-time.