Mothra was the protector of an ancient civilization, which was beseiged by the Xilien people thousands of years ago. Mothra was killed during the battle, along with the majority of the human population, and the continent she resided on sunk into the sea. Fortunately, she was survived by two larvae, and the Mothra lineage lived on.

In modern times, after the Xiliens had returned, Mothra was called upon to help Godzilla. However, she was intercepted by a rebuilt Gigan, and the two fought once more. Though Gigan initially had the advantage (even impaling her and slicing off a piece of her wing), Mothra managed to permanently end the cyborg in a kamikaze attack.