Kim Jae-joong, also known mononymously as Jaejoong in South Korea and Jejung/J-Jun (ジェジュン) in Japan, is a South Korean singer, songwriter, actor and director. He is a member of the Korean pop group JYJ and was one of the original members of boy band TVXQ, where he was formerly known by the stage name Hero Jae-joong. Since 2013, he has expanded his range of activities as a solo artist, and in 2023, he formed his own agency iNKODE where he serves as the Chief Strategy Officer.

JYJ is a South Korean boy band formed in 2010 by Kim Junsu, Kim Jae-joong, and Park Yoo-chun, the three former members of TVXQ. Their group name is taken from the initial letters of each member's names. The group was formerly managed by C-JeS Entertainment in Korea.