Lee Joon, born in Seoul, South Korea, is an idol, singer, dancer, actor, voice actor, radio DJ and model under Prain TPC (프레인TPC). He was a member of the Korean boy band MBLAQ (엠블랙) until the end of November 2014, when his contract with J. Tune Camp (제이튠캠프) officially ended. He signed with Prain TPC in 2015. He enlisted in the military on October 24, 2017, and was discharged on December 19, 2019.
During a 2010 interview, Lee revealed that he suffers from both insomnia and severe bipolar disorder.