In a short interview with the Wall Street Journal, Samuel L. Jackson let slip that Elizabeth Olsen has joined the cast of Avengers: Age of Ultron as the Scarlet Witch, joining James Spader as Ultron himself and an as yet unnamed actor as the Scarlet Witch’s brother Quicksilver.
Although Jackson doesn’t name Olsen in the role, the implication was apparently clear enough for the WSJ to add that to Jackson’s quote in the article. Olsen is the younger sister of Mary-Kate and Ashley Olsen, and is notable for her recent stand-out roles in Silent House and Martha Marcy May Marlene.