Dark Samus

Dark Samus is a character in the Metroid series who first appeared in Metroid Prime and again in Metroid Prime 2: Echoes. She is also the main villain in Metroid Prime 3: Corruption,

Dark Samus was created when Samus Aran destroyed Metroid Prime. As it was dying, Metroid Prime stole the Phazon infected Phazon Suit from Samus as it was absorbing all of the Phazon in the area. If you defeat Metroid Prime with 100% of all the item, you may watch as Dark Samus is born. In Metroid Prime 2: Echoes, Dark Samus "officially" appears in the Metroid series. Dark Samus cannot survive without Phazon and ravages the Space Pirate base on Aether and all of Dark Aether. It is encountered three times in the game, finally being destroyed on Dark Aether and (as it seems, intentionally or not) removing the Phazon blocking the only Light Portal back to Aether. Then Dark Samus reforms above Aether as Samus leaves the planet.

Dark Samus corrupts all the hunters on planet Norion in their attempts to stop the Leviathon Seed from crashing into the planet. Dark Samus gradually takes over all of Samus Aran's fellow hunters, and finally Samus faces Dark Samus in Phaaze, where after it's defeat, absorbs itself into the Aurora Unit 313.After the Aurora Unit 313 is destroyed, Dark Samus appears for a final time and disappears in a fantastic explosion, thus supposedly ending it's life.

Although Dark Samus does have many moves based off of Samus Aran, it has developed a lot of its own moves. In Metroid Prime 2: Echoes, Dark Samus can turn invisible and regenerate after huge explosions. In Metroid Prime 3: Corruption, it shows the ability to fly at the cut-scene in the beginning. In the final battle it can heal, create clones called dark echoes, make phazon crystals fall from the sky, make a tornado with it's clones, and shoot some kind of plasma beam. It is also a master of its Phazon Beam.

Super Smash Bros. Brawl
Dark Samus appears as a trophy in Super Smash Bros. Brawl for the Wii. In a cooperative event match there's a silhouette of Samus that's called Dark Samus, though doesn't look like her incarnation from the Metroid Prime series.

Trophy description
"A twin image of Samus, encountered near the beginning of Metroid Prime 2: Echoes. Dark Samus is identical to Samus in every way but color--she even uses similar attacks. There are many theories on the origin of Dark Samus, but none are proven. Dark Samus uses Phazon for energy and can absorb it to heal damage. Samus encounters Dark Samus a number of times."