Loona (stylized in all caps or as LOOΠΔ and L∞na) is a South Korean girl group formed by BlockBerry Creative. They officially debuted on August 19, 2018 with the EP + +. The group is composed of 11 members: Heejin, Hyunjin, Haseul, Yeojin, ViVi, Kim Lip, Jinsoul, Choerry, Yves, Go Won and Hyeju (formerly Olivia Hye).

Originally, a 12-member girl group, Chuu was removed from the lineup on November 25, 2022 due to a contract dispute. The remaining members of the group departed Blockberry Creative later that year, putting the group on an indefinite hiatus.

Starting in October 2016, members and sub-units were introduced with music videos and EPs released over the course of 18 months.

The group’s revealed sub-units are the following:

1) LOOΠΔ 1/3, consisting of the three first girls, HeeJin, HyunJin and HaSeul, making up the ‘3’, the fourth girl, YeoJin making up the ‘/‘, and fifth girl Vivi making up the '1’. They released Love & Live in March 2017, which deals with the themes of first love. The following month, they released Love & Evil, which deals with themes of experiencing first heartbreak.

2) LOOΠΔ / ODD EYE CIRCLE is comprised of members Kim Lip, JinSoul and Choerry. Their album Mix & Match was released in September 2017, and its repackage Max & Match the next month. The concept showcased was a girl crush, with the main theme being to not wait for love, but actively look for it and take initiative.

3) LOOΠΔ yyxy is composed of members Yves, Go Won and Hyeju (formerly Olivia Hye) in the third and last known sub-unit. They released the EP beauty&thebeat in May 30, 2018, which featured the lead single “love4eva”, a collaboration with Canadian singer Grimes. Originally as 4, Chuu, was removed on November 25, 2022 due to a contract dispute.