Not much has been revealed about the history and origin of the woman known only as Astra. She claims to have been an original recruit for the Brotherhood of Evil Mutants, led by the self-proclaimed mutant ruler, Magneto. Astra left the group under mysterious circumstances before it made its first public appearance fighting the mutant group called the X-Men. She claimed that Magneto "emotionally beat" her.
She continued to track Magneto's subsequent activities. Her fascination with Magneto led her to create a sophisticated clone of him, one that was "created to be even stronger than Magneto, lacking the self-restraint Magneto placed on his powers years ago." However, in order to create the clone, Astra had to restore the real Magneto to health, who had been placed in a catatonic state by Professor Xavier. Magneto, once restored, fought the clone and the battle ranged to South America, where he defeated the clone and fled.
The clone found a name for himself, Joseph, and soon found himself with the X-Men, developing relationships with them. Presumably during this time, Astra was consumed with other plans, or was otherwise occupied elsewhere.
Astra first made herself known by re-capturing Joseph when he was wandering in the Israeli desert, believing himself to be the real Magneto. Astra revealed her hand in Joseph's creation.
She then used Joseph to infiltrate Magneto's base, at a time when Magneto was trying to realign the Earth's electromagnetic spectrum as a part of his war against humanity. Attempting to kill Magneto in order to be seen as Earth's savior, Astra wanted to use Joseph to control the energies that Magneto had tapped into. Joseph, however, after defeating Magneto, ended up repairing the damaged to the magnetosphere by merging with it.
Astra was defeated by the X-Men's Nightcrawler, whom she professed to recognize from his youth, but she used her teleportation powers to escape, vowing to return and face the X-Men again.
It was assumed for a while that she was killed by Apocalypse, but she survived.
Astra kept her powers after the Decimation. She restored Joseph's body and together they formed a new Brotherhood. They fought with Magneto, and as a result, Astra was caught and locked up in the X-Brig on the Utopia.