KELT9b (켈트나인) is a five-member girl group under US Media Group. They made their debut on November 23, 2024 with the digital single "Uncrushable".

Initially, the group was supposed to be divided into two sub-units: DMZα and DMZβ.[1] However, since then, ten trainees have left the group line-up and additionally their debut has been delayed due to the COVID-19 pandemic. Hence, the group has been reformed with a new concept for debut.