The Scarlet Witch (Wanda Maximoff) is a character appearing in American comic books published by Marvel Comics. Created by writer Stan Lee and artist Jack Kirby, the character first appeared in The X-Men #4 (March 1964) in the Silver Age of Comic Books. Originally said to have the ability to alter probability, the Scarlet Witch has been depicted as a powerful sorceress since the 1980s and on occasion has become powerful enough to alter reality by tapping into greater energy sources.
The Scarlet Witch is first depicted as a reluctant supervillain along with her twin brother, Pietro Maximoff/Quicksilver, both founding members of the Brotherhood of Evil Mutants. A year after her debut, she joined the Avengers superhero team and ever since has often been depicted as a regular member of that or related teams (such as the West Coast Avengers and Force Works).
For most of her comic book history, the Scarlet Witch is portrayed as a mutant, a member of a fictional subspecies of humans born with an "X-gene" that grants superhuman abilities and traits, although multiple stories also say the nature of her mutant powers was influenced by the High Evolutionary experimenting on her when she was a child. A 2015 storyline revised Wanda's origin, establishing that her superhuman traits are entirely a result of experimentation done by the High Evolutionary and inherited magic abilities. Like Franklin Richards and other characters, her genetics are such that standard X-gene tests gave a false positive, meaning she was not actually born a mutant.
Content gathered from Wikipedia