Good Day (Korean: 굿데이) was a South Korean girl group formed by C9 Entertainment, with ten members: Heejin, Genie, Cherry, Chaesol, Nayoon, Jiwon, Haeun, Viva, Bomin and Lucky. They debuted on August 30, 2017, with their first and only EP All Day Good Day.
It is said that the group has disbanded, as C9 Girlz (later named Cignature) was announced on November 11, 2019.