Scarlet Witch

"It's not a world of spies anymore, not even a world of heroes. This is the age of miracles, doctor. There is nothing more horrifying than a miracle!"

- Baron Strucker Scarlet Witch is a character in the Marvel Cinematic Universe set to appear in Avengers: Age of Ultron. She is the twin sister of fellow Avenger Quicksilver. She is portrayed by actress Elizabeth Olsen.

Appearances
The Avengers: Earth's Mightiest Heroes Wanda along with her father and brother, went to Avengers Mansion, to claim the Wasp for the Brotherhood of Mutants, believing that she is a mutant, due to a rumor in the news.

Facing the Avengers, Wanda uses her Hex Blasts on a garbage can, causing it to explode and thus defeating the Wasp, who understand the reason behind their arrival, claiming that she is not a mutant, while Magneto attacks the anti-mutant protesters were in the mansion because of what one of them threw a brick at him.

This makes Scarlet Witch and Quicksilver went against their father, who imprisons them with pieces of metal, almost strangling his own daughter with her ​​powers, but being released by the Wasp, who starts firing her stings to Magneto.

When the Avengers are released from the metal bars, attacked Magneto, who escaped when Wanda and Pietro attacked him, demanding there should be a better way, they state because his anger makes him blind and cruel as those who fight, but Magneto, claiming that Mutantkind is the best way, and when the war came, they will see the truth, and be on his side, or be destroyed.

After the attack, Iron Man tells Wanda and Pietro to come with them, and Jan explains to the twins that she is not mutant, but the Avengers would not mind if  they are, and also speaking to the crowd that regardless of whether they are, they fight against the bad guys together, Quicksilver grabs the Scarlet Witch and escape, but not without telling the Avengers that they have given the siblings something to think about.

Scarlet Witch can be seen on Fury's wall of Skrull suspects in the episode "Infiltration".

Ultimate Spider-Man
Scarlet Witch makes a cameo in the Ultimate Spider-Man episode "Flight of the Iron Spider".

Captain America: The Winter Soldier
Scarlet Witch and Quicksilver appear in a mid-credits scene, where she and her brother were confirmed to have not been present at SHIELD's headquarters at the time HYDRA was defeated there and Operation Insight was shut down due to Baron Strucker's actions. Strucker also revealed he intended to use them for an unspecified purpose.

Avengers: Age of Ultron
Director Joss Whedon has stated that the Scarlet Witch and her brother, Quicksilver, will appear in the 2015 film Avengers: Age of Ultron. Whedon revealed that she would not be wearing her costume from the comics. In August 2013, The Hollywood Reporter reported that Marvel Studios was in negotiations with Elizabeth Olsen to play the character.

Trivia

 * After 50 years of appearing in various Marvel publications, Scarlet Witch's cameo in the 2014 film, Captain America: The Winter Soldier marked her first ever theatrical live-action appearance. Although, she did also appear in a 1999 Got Milk commercial.
 * In the comics, Scarlet Witch is married to The Vision.