METROID PRIME 3: CORRUPTION
Dark Samus is a creature that was spawned when Samus' suit was absorbed into Metroid Prime. From that moment on, she exists to spread the corruptive substance "Phazon." In Metroid Prime 3, she succeeds in infecting Samus and three of her bounty hunter comrades. The latter three succumb to the Phazon and then absorbed into Dark Samus. Deep within Phaaze, Samus has her final confrontation with her dark doppleganger, and destroys her for good.
This anti-heroine/villainess and the game "Metroid Prime 3: Corruption" are copyrights of Nintendo.