Saturn Queen. Born Eve Aries of Titan (one of Saturn's moons) in the 21st Century. She is a high-level telepath who, like most telepaths from her world, has a complex set of urges to do good or evil (in her case, evil) that are hard to control. She was a founding member of the Legion of Super-Villains and often fought Superman, in addition to the Legion of Super-Heroes.
As CRISIS ON INFINITE EARTHS approached, Saturn Queen and her associates, Lightning Lord and Cosmic King, went back in time and murdered the Kents before they could discover the infant Superman. They also killed the robber who murdered Batman's parents. They then took the two and raised them as if they were their own children. When they were older, Batman and Superman became Saturn Queen's enforcers, terrorizing anyone who poses the will of their "adoptive parents". Oddly enough, Saturn Queen became concerned that what she and her associates had done would have irreversible consequences, but she also grew fond of this reality, and of her "boys."
Eventually, however, Wonder Woman opposed her regime. She killed Batman, but in turn was killed by Superman. During the melee, an enormous eruption of energy destroyed the whole timeline, but another one took its place because of the intervention of an older version of Superman (from Alan Moore's "Whatever Happened to the Man of Tomorrow?" timeline) and Darkseid, Lord of Apokolips. Saturn Queen and her LSV associates were replaced as rulers with Ra's al Ghul and became temporal anomalies in the newborn present. Superman and Batman, both restored, attacked the villains, and then they took them to the moment in time in the 31st Century before the villains first changed the timeline to prevent everything that had happened up to this point from happening to begin with. Superman and Batman turned Saturn Queen, Lightning Lord, and Cosmic King over to the Legion of Super-Heroes. Yet, once Superman and Batman return to the 21st Century, the events of CRISIS ON INFINITE EARTHS happened, and the 31st Century as wiped from existence.
Be that as it may, Saturn Queen survived the Crisis. She slipped through the cracks during the recreation of the universe and found herself stranded in the Phantom Zone, where she encountered Ultraman, another survivor of the Crisis. She came to see him as a suitable replacement for the version of Superman that was her son in a previous reality and took control of his mind, making him believe that she was his mother. Thanks to the events of INFINITE CRISIS and Alexander Luthor of Earth-3, Saturn Queen and Ultraman found themselves on a world similar to the one she had created with the LSV. They went about making the capitol city of Kandor in their image, with Ultraman enforcing her will through acts of terror,as she ruled behind the scenes. They were opposed by Power Girl and Supergirl of the main reality, but Saturn Girl defeated them with her vast telepathic prowess. She then tried to force Supergirl to marry Ultraman as a way to ensure that her perfect world reach its apex. However, her plans were foiled when she telepathically entered Power Girl's mind. She lost control of both Supergirl AND Ultraman, and she was last seen cradling Ultraman's body in her arms as the rebellion started by Power Girl and Supergirl closed in around her.
And then came FLASHPOINT. In the newly restructured reality, Saturn Queen delighted in probing deeply within someone's mind and exposing their darkest desires. She believed that all sentient life forms had deviance laced in their kind and only pretended to perform good deeds to hide their twisted desires. She went about recreating the Legion of Super-Villains, only this time with a smaller cadre of members, and plotted to kill the powers watching over the universe so that chaos and anarchy could run rampant without opposition. She succeeded in destroying the Rock of Eternity, but she and the LSV were later finally defeated by the Legion of Super-Heroes.
As of DC UNIVERSE REBIRTH, Saturn Queen has yet to be seen.