Screamthief was originally a young girl from a town in upstate New York, who was ostracized by the townsfolk due to her appearance- white skin and hair and red eyes. She built up fear and resentment for years, until she discovered the potential of the Fear-Rings to transform fears into reality. Naming herself Screamthief, she began a reign of terror in Metropolis, creating monsters battled by the Justice League. Her attack culminated in taking down Superman with the so-called Superslaughterer.
Screamthief began absorbing the fear created over the next 10 days, as a crime spree swept Metropolis that the League was hard-pressed to stop. Martian Manhunter masqueraded as Superman, which bolstered the citizens of Metropolis and took away Screamthief's source of fear. She retaliated by returning to her hometown and attacking with a new crop of nightmare monsters, only to have "Superman" encourage the populace to new bravery. Screamthief attacked "Superman" with the Superslaughterer, which failed; so she summoned up a giant shark monster to eat him. It was then that the Martian Manhunter realized the fear she was tapping now- her own. Confronting her in his true form, he made peace with her- she surrendered the Fear-Rings, then dissipated.