Lee Chang-sun, better known by his stage name Lee Joon, is a South Korean actor, singer, model and DJ. He is best known as a former member of the South Korean boy band MBLAQ. He had notable roles in Gapdong (2014), My Father Is Strange (2017), The Silent Sea (2021), Bulgasal (2021).

MBLAQ is a South Korean boy band created by South Korean singer Rain under J. Tune Camp. The group consists of Seungho, G.O, and Mir, and formerly Lee Joon and Thunder. The group debuted on October 15, 2009, at Rain's Legend of Rainism concert.