Q.O.S (Queens of Sound) was a South Korean girl group that debuted in 2020 under VT Entertainment. The group originally had five members: Terra, SeulE, Lily, Dahee, and Nicky. Dahee left shortly after debut, and Nicky departed in 2021, leaving Terra, SeulE, and Lily as the final lineup. They focused on pop and R&B sounds during their active years. The group has not promoted since 2022 and is believed to have quietly disbanded.