Cho Ha-seul (조하슬), also known simply as HaSeul (하슬), is the third revealed member of LOONA, a member of its first sub-unit, LOONA 1/3, and the girl group's leader. She is a South Korean singer. Currently, she is signed with MODHAUS agency under their ARTMS project. In October 2023, she made her solo redebut. HaSeul is also a trained opera singer.