Dead Girl was once a young mutant woman named Moonbeam ( her last name was neaver revealed) who moved to New York to become an actress. Murdered by a one-night stand, she revived using her mutant power and killed her murderer. Relocating to California, she became a freelance adventurer, and soon joined the publicity-seeking mutant team X-Statix.

Dead Girl can regenerate from any lethal attack, she can also communicate with corpses and other dead things, often getting images and half storys from them. Later she is able to phase through objects and walk on air.

X-Statix eventually decided to retire on their wealth after one final mission; Dead Girl accompanied her teammates despite an unexplained illness which ultimately re-killed her.