Scarlet Witch

Wanda Maximoff started as a villain. She and her brother Pietro debuted in X-Men #4 as members of Magneto's Brotherhood of Evil Mutants, coerced into service by a debt, and defected to the Avengers by issue #16 as part of Cap's Kooky Quartet. Her original power was a vague hex that made improbable bad luck happen; six decades of escalation turned that into the ability to rewrite reality, and Marvel has never fully closed the gap between the two.

The upgrade came from Agatha Harkness and the Darkhold. Wanda's chaos magic, tied to the elder god Chthon who was imprisoned beneath Mount Wundagore where she was born, gives her probability manipulation, energy projection, telekinesis, and at full stretch the power to alter the fundamental structure of the universe. She is formally classified as a Nexus Being, a fixed point that reality organises itself around, which is why her breakdowns are cosmological events.

Her defining tragedy is her children. Wanda married the synthezoid Vision, conceived twins through magic, and then learned in Avengers West Coast that Billy and Tommy had never existed as anything but fragments of Mephisto's soul. The suppressed memory detonated twice, first in Avengers Disassembled, which killed Vision and Hawkeye and dissolved the team, and then in House of M, where she rebuilt the world so everyone got what they wanted and ended it by erasing the powers of roughly ninety per cent of mutantkind with three words.

Wanda spent the 1960s and 1970s as an Avenger, married Vision in Giant-Size Avengers #4 (1975), and headlined the Vision and the Scarlet Witch miniseries in 1982 and 1985, in which she gave birth to twins. Then John Byrne's Avengers West Coast dismantled the family: Vision was disassembled by a government black op, and the children were revealed as splinters of Mephisto, an event that broke Wanda's mind.

Brian Michael Bendis and David Finch's Avengers Disassembled (2004) had her unknowingly conjure attacks that killed Hawkeye and Vision and destroyed Avengers Mansion, ending the team. The follow-up, House of M (2005) with Olivier Coipel, gave her a world where mutants ruled and Magneto was king, and when it collapsed she said no more mutants and depowered nearly the entire species, setting up a decade of X-Men stories.

Allan Heinberg and Jim Cheung's Avengers: The Children's Crusade (2010-2012) brought her back, revealed Doctor Doom's involvement, and reincarnated her children as Wiccan and Speed. Rick Remender's Uncanny Avengers and AXIS then declared she and Pietro were not mutants and not Magneto's children, a retcon later complicated again in The Trial of Magneto (2021). James Robinson's Scarlet Witch (2015) and Steve Orlando's later solo work grounded her as a working sorceress.