Oh Jong-hyuk (born February 16, 1983) is a South Korean singer, actor, and member of the iconic boy band Click-B. He debuted with Click-B in 1999 under DSP Media, gaining fame as part of the first-generation K-pop idol scene. In 2006, he launched a solo career under the stage name OJ, releasing the album OJ Issue, followed by additional albums and singles that showcased his musical versatility. Oh has also ventured into variety shows, notably appearing on Law of the Jungle (2013–2014) and King of Mask Singer (2015), where he performed under the alias "Lonely Man Leon." His acting pursuits have further solidified his presence in South Korea's entertainment industry. Educated at Dankook University High School and Kyonggi University, Oh completed his mandatory military service in the Marine Corps from 2011 to 2013, serving as an active-duty officer. Currently signed with Bless Ent, Oh remains active in music and television, contributing to South Korea's vibrant entertainment scene. In 2024, Oh released a new single "Love is like that 2024".