The unknown woman known only as the Leper Queen was the leader of the Anti-Mutant group known as the Sapien League. She allegedly started the group because of her hatred of mutants. This hatred stemmed from the fact that her daughter was born a mutant and her powers ended up killing herself and disfiguring the Leper Queen. She killed many mutants in cold blood and after the events of M-Day organized her Sapien League to attack the Xavier Institute. This attack was defeated by the combined efforts of The X-Men and Sentinel Squad O.N.E.

She has recently sent a team of Sapien Leaguers after the now former X-Men Havok and Polaris. They escaped but soon the Leper Queen and Polaris were sucked into Apocalypse's ship. Polaris was Apocalypse's choice for his horseman of Pestilence, because Leper Queen wanted it too badly. She soon somehow escaped the celestial ship.

She was added to the ranks of the Purifiers. She was then injected with the Transmode virus by Bastion. Soon she brought Beautiful Dreamer and Fever Pitch to different anti-mutant rallies. Since they were injected with a stronger version of the Legacy Virus, there powers were to strong for them and they killed all the people there and, presumably, themselves. She was actually upset at killing all the humans though. She also later injected a captured Surge, Hellion, and Boom-Boom with the Transmode virus as well. She sent Surge and Hellion off one way and tried to make the X-Force team chose who to save. However, Cyclops suddenly sent X-Force into the future and they were unable to help either. The Leper Queen was mad because she wanted Boom Boom to lure X-Force to her so that they would kill her, because she was unable to kill herself thanks to Bastion. She then shot Boom-Boom, saying that they had failed them both. However, X-23's timely return instead saved Boom-Boom and killed the Leper Queen, resulting in a divergent reality, Earth-95313^[1], where Tabitha did, indeed die.