"You think because we're mutants we're better than them. That we deserve to rule. That's what you wanted and I gave it to you. But look... Look what it becomes. Even when you get what you want, you're still this horrible man. We're not the next step. We're not gods. We're freaks!! Look at us, daddy! We're freaks!"
Scarlet Witch is a Marvel Comics character, now widely known as the instigator for several arcs like Avengers Disassembled and House of M. Reader opinion right now is divided to two: Either she is a tragic figure broken further thanks to the meddling of Brian Bendis, or she is a downright mentally insane figure who is a bitch. Most of them are the former opinion, however.
She first appeared in "X-Men" vol. 1 #4 (March, 1964), created by Stan Lee and Jack Kirby. Wanda Maximoff, daughter of Erik Magnus Lehnsherr (AKA Magneto), was born with magic-like mutant powers. With her twin brother Pietro (aka Quicksilver), she was raised in the Wundagore Mountains by gypsies. As it turned out, Wundagore served as a prison for the Elder God Chthon who imparted a fraction of his power to Wanda so that she might one day serve as his vessel. Eventually, she and Pietro were recruited into the Brotherhood of Evil Mutants by their father (though neither he nor they were aware of their relationship at the time), and for a while they were both enemies of the X-Men. Eventually Magneto was imprisoned and, having nowhere else to go, Wanda and Pietro applied for membership in The Avengers along with another ex-villain (Hawkeye/Clint Barton). Captain America (comics) accepted them, as the roster was then empty (except for himself) and thus they converted to the side of good.
Wanda fell in love with and married The Vision, the Avengers' Ridiculously Human Robot, but the marriage was troubled when she became pregnant. Wanda had used her powers to conceive with the android, and give birth to twin sons, only to later find out that she had drawn on the demon Mephisto's magic, who proceeded to erase their existence. The time-traveling villain Immortus claimed he had set up all these events, including her marriage to Vision, with the goal of driving Wanda insane, since she was the "living anchor of reality" of her universe. He intended to use her to reshape reality to his will, but the Avengers stopped him. She then suppressed her memory of her children, and it seemed she could move on (even though she had to break up with Vision afterwards).
Alas, it wasn't meant to be.
While discussing just how complicated having kids would be for a superhero, Janet/the Wasp slipped up and briefly mentioned Wanda's "kids" to her, leading Wanda to discover the truth and consequently suffer a complete breakdown. Thus began the arc of Avengers Disassembled, where Wanda lost control of her powers and killed off several Avengers, including Vision and Hawkeye, without even being physically present -- she spent most of the arc being kept company by illusions of her children until the Avengers came to confront her. She was eventually disabled by Doctor Strange, only for Magneto to come and take her to Genosha to atone for his neglect. But her rampage destroyed the Avengers, since they couldn't go on after to the damage she had caused.
Tensions arose between Magneto and Professor X in Genosha, because Xavier refused to help Wanda as she attempted to bring her husband back to life. In the end, Magneto retreated further and Xavier called in the X-Men to decide on Wanda's fate; they agreed to kill her. Pietro overheard this news and in horror pleaded with Wanda to take immediate action. She ended up rewriting reality so Mutants became the dominant species, and Wanda had a human body in which she could have her sons. This was House of M (check the main article for the details of what happened).
At the climax of House of M, Wanda turned on Magneto after seeing what he had done with his mutant-dominated world, prioritizing mutants over his children and even killing Pietro in a rage. To get revenge on him and Professor X, who refused to help her, she uttered the words: "No more mutants", and reverted the world back to normal, depowering 90% of all mutants in the process and causing many deaths. Subsequently, she lost her memories and powers and retreated to a secluded life on Wundagore. Clint Barton, now revived, paid her a visit and eventually decided that she was better off not knowing what she had done.
The Scarlet Witch reappeared and instigated the formation of the Mighty Avengers (although some heroes like The Young Avengers' Stature were justifiably angry at her), which included Pietro himself. However, it transpired that this was not the real Scarlet Witch but the trickster Loki using her image as a disguise.
In the 2011 Avengers: The Children's Crusade, Magneto teamed up with Wiccan to find Wanda and get some answers. She was discovered living with Doctor Doom as his engaged bride, with no memory of her past. After an intervention by Iron Lad, Wanda and the Young Avengers were transported into the past, and a chance encounter with the Dread Jack of Hearts reawakened her memory. Declaring "More mutants," she touched the depowered mutant Rictor and restored his abilities. But the X-Men came calling... as did the Avengers.
- Actually a Doombot: In the Children's Crusade mini.
- Break the Cutie: Taken Up to Eleven. Just...see above.
- Brother-Sister Incest: Wanda's relationships with her brother Pietro sometimes look a little 'too close'. In Ultimate Marvel Universe they are outright stated to be lovers.
- Fake Brit: In the second X-Men Legends game, she was voiced by Jennifer Hale with a British accent. Never mind that Wanda isn't even British.
- Heel Face Revolving Door: She's gone from evil to good to mad to...
- ... good again, for now anyway.
- Mad Mutant Dictator's Beautiful Daughter.
- Hot Mom: To Wiccan and Speed of the Young Avengers...sort of. She's not their biological mother, but their souls (or at least part of them) are those of the children she created, reborn.
- Not to mention she has an alternate reality daughter with Nightcrawler.
- Hot Witch: Mutant powers? Magic? Mutant powers that let her tap into magic? No matter which, she qualifies.
- Lady of Black Magic
- Oblivious to Love: In the Heroes Reborn universe Wanda had an unrequited crush on Captain America (comics).
- Power Creep, Power Seep: When she started out, she had only the power to create "hexes," which would cause bad things to happen. Her powers have since expanded to the point where she is a Reality Warper almost on par with Q.
- Powered by a Forsaken Child: Several Big Bads, such as Immortus and Morgan Le Fay, used her as their power source.
- The origin of her powers is a combination of her natural mutant abilities and being infused with a portion of the powers of Chthon, an immensely powerful demonic entity, who intended to use her as his host. And still does.
- Reality Warper: And how!
- Scarlet Fever
- She's Back: The formation of Mighty Avengers teased this, but it was really Loki in disguise. Played straight in Children's Crusade #6 -- Wanda's alive, repowered, and back to her old self. Which arguably makes things even more complicated.
- Trauma-Induced Amnesia
- Truly Single Parent: Created her two sons with nothing but her reality warping powers. Or so it was in the beginning.
- Unwanted Harem: Being the only female in Magneto's earliest incarnation of the Brotherhood of Evil and the only female Avenger for a while probably caused a lot of it.
- Winds of Destiny Change: Trope Namer. What her mutant power was originally thought to be. Everyone underestimated.