South Korean singer and actor Lee Chang-sub was born on February 26, 1991, in Suwon, Gyeonggi-do. He made his debut as a lead vocalist of the South Korean boy group BtoB in March 2012, under Cube Entertainment. The group initially focused on both ballads and dance-pop, gaining popularity for their vocal prowess. BtoB’s early hits like "Insane" and "Wow" earned them a loyal following. In 2016, BtoB's album New Men, featuring the hit single "I'll Be Your Man," marked their shift towards a mature image and sound. As part of BtoB, he contributed to many popular songs like "Last Day," "Killing Me," and "Melody," among others. In parallel with his music career, Changsub also enjoyed great popularity in the world of musical theater, making his official debut in 2017 in the Korean adaptation of Boys Over Flowers. Over the following years, he would also land lead roles in musicals such as Napoleon, Edgar Allan Poe, Dogfight, and Iron Mask. Changsub made his solo debut in 2018 with the release of his first EP, Mark, a Top 5 entry that included the lead single "Gone." The album showcased his emotional vocal range and musical diversity. Before that, he had also released the Japanese extended play bpm 82.5, which peaked at Number 12 on the Oricon charts. In addition to his solo work, Changsub has also been featured in several film and TV series soundtracks with songs like "Freedom" (from 2022's Doctor Lawyer) and "Love from a Real Heart" (from 2023's It Was Spring), a sentimental ballad that reached Number 120 on the South Korean Circle Chart. In September, 2024, he released 1991 and his second EP, ENDAND on October 22, 2025.