While many girl groups have experienced lineup changes, some departures had a particularly large impact on the group's popularity, identity, or future. These are often considered the most affected girl groups in K-pop history.

Member departures affect every K-pop group, but historically, girl groups often experience a greater immediate impact, while boy groups are more likely to survive long-term lineup changes. This is not a hard rule, but it is a trend that can be seen throughout K-pop history