Moon Byul-yi, known professionally by her stage name Moonbyul, is a South Korean rapper and songwriter signed to RBW. She is a member of the South Korean girl group Mamamoo and its sub-unit Mamamoo+. She made her debut as a solo artist in May 2018, releasing the digital single "Selfish". According to the Korea Music Copyright Association, Moonbyul has songwriting credits on over 100 songs, making her one of the most credited female artists in the Korean music industry.