Moon Byul-yi, known professionally as Moonbyul, is a South Korean rapper, singer and songwriter under RBW Entertainment. She is a member of the girl group MAMAMOO and its sub-unit MAMAMOO+. Moonbyul made her solo debut in May 2018 with the digital single Selfish. According to the Korea Music Copyright Association (KOMCA), she has songwriting credits on over 100 songs.