Gugudan (Korean: 구구단), also stylized as gu9udan or gx9, was a South Korean girl group formed in 2016 by Jellyfish Entertainment and the company's first girl group. The group debuted on June 28, 2016, with their EP Act. 1 The Little Mermaid. The group was composed of eight members: Mimi, Hana, Haebin, Nayoung, Sejeong, Sally, Soyee, Mina, and previously Hyeyeon until her departure from the group in October 2018.
Following two years with no group activities, Gugudan disbanded on December 31, 2020.