The long-standing Black Queen of the Hellfire Club's Inner Circle, Selene Gallio professes to have lived for several millennia, and to have been a foe of the ancient sorcerer, Kulan Gath. In past ages, she was renowned as a sorceress whose power was feared and respected by other magic users. She eventually came to live in the ancient Roman Republic. At some point, Selene established herself as the Goddess of the Moon of Arthurian legend. Perceived by various sources as being a powerful sorceress, Selene is actually one of the long-lived mutants known as the Externals, possibly the oldest. Over the millennia, her worshippers grew into a world-wide cult.

In her efforts to obtain power, Selene was responsible for the establishment of the hidden Amazonian city Nova Roma. These supposedly Roman citizens were said to have fled the first century B.C. Italy and lived there for roughly two thousand years, and was supposedly where Selene first founded her Cult of Fire as its Black Priestess. (However, it has been since revealed that Nova Roma was a massive illusion maintained by Selene and her minion, the mutant known as Empath, to hold its citizens, really, kidnapped British and American tourists, captive.) Prior to this revelation, however, Selene posed as the wife to Nova Roma Senator Marcus Domitius Gallo, whose plot to abolish the republican Nova Roman government led to her to first encounter students of Charles Xavier in the form of the New Mutants.

Selene soon after traveled to New York, where members of her world-wide cult had a church. The leader of the cult, Friedrich von Roehm, was also a member of the Hellfire Club. With Von Roehm's help, Selene entered the Inner Circle of the Club and rapidly rose to the high rank of Black Queen. As the Black Queen, Selene had tried numerous attempts to overthrow her current leader, the Black King Sebastian Shaw. One such attempt brought Jean Grey (in reality, the Phoenix Force,) into the Inner Circle, which led to the intervention of the X-Men in the Club's plots.

At one point, she helped formed the Upstarts, a group of hedonistic young mutants who played a game when killing off other mutants. Although she never directly participated in the Upstarts’ plots, she enjoyed the benefits of their decimating the ranks of the Inner Circle. Later, for reasons of her own, Selene took it upon herself to begin killing the remaining members of the Externals, absorbing their life forces. Despite the efforts of X-Force, Selene escaped.

In a recent plot against the Hellfire Club, Selene usurped the Black King`s position and replaced him with her demonic ally, Blackheart. Her plan was foiled by the combined efforts of the Fantastic Four and the Shadow Hunters.

She then blackmailed Sunspot into joining the Hellfire Club by claiming that the Damocles Foundation, formerly run by the Externals’ Gideon, was seeking to begin a new experiment similar to the process that created Sunspot’s “evil twin,” Reignfire. The two raced to stop it, and they were joined by X-Force. However, Selene wanted the process for herself, and she subdued Sunspot and X-Force. She then offered to resurrect the spirit of Juliana, Sunspot’s first love, in exchange for his agreement to become a member of her new Hellfire Club, and Sunspot agreed.

As always, Selene remains extremely ambitious and deceitful, and should always be approached with caution.