Jeong Yun-o (Korean: 정윤오; born Jeong Jae-hyun (Korean: 정재현); February 14, 1997), professionally known as Jaehyun, is a South Korean singer, rapper, songwriter, and actor. He is a member of the South Korean boy band NCT and its sub-units NCT 127 and NCT DoJaeJung. Jaehyun is recognized as one of NCT's all-rounders for his unique baritone vocals and skills in rapping and dancing.

First introduced in December 2013 as a trainee under the pre-debut team SM Rookies, he debuted in April 2016 as a member of the rotational unit NCT U and as a member of Seoul-based fixed unit NCT 127 in July 2016. He later joined the fixed unit NCT DoJaeJung in April 2023. NCT are noted as one of the most successful K-pop acts, both domestically and internationally, selling over 32 million[a] records within only seven years.

As of 2023, Jaehyun has released two solo singles: "Forever Only" and "Horizon", both as part of the NCT Lab project. Apart from music, he has also hosted the radio show NCT...