Lee Chang Yoon, known professionally as E-Tion, is a South Korean singer, dancer and member of ONF (온앤오프; short for ON N' OFF). He graduated from Woosuk High School and was enrolled in the Japanese program at Hanyang Cyber University but is officially on a leave of absence. Before debuting, he was a trainee for 3 years and was introduced as part of WM Boys with their first appearance as B1A4's backup dancers at the 2016 Dream Concert in Seoul. He was featured as a dancer in the Korean version of the web drama "Loss:Time:Life" and gave a performance at IDOLCON just a few months before debuting. He made his official debut in August 2017 as the group's ON Team member and lead vocalist with their 1st EP, "ON/OFF". In 2018, the group signed a contract with Victor Entertainment (ビクターエンタテインメント) and made their Japanese debut and held a concert in Tokyo. In 2020, all the members entered MNet's "Road to Kingdom" and finished in 2nd place and he had his acting debut with a role in the web drama "Can I Step In?". In 2021, all members (except U) decided to enlist for their mandatory military service around the same time, so he enlisted on December 28 and was discharged on June 27, 2023. After his release, the group is now active again and is represented by WM Entertainment (WM엔터테인먼트).