Ultron used the Infinity Mind Stone, encased in Loki's scepter, to create a body out of Vibranium and synthetic human tissue so that he could be invincible. The Avengers, however, captured this body before Ultron could upload his mind into it. Bruce Banner and Tony Stark uploaded J.A.R.V.I.S' artificial intelligence into the body, who awoke after Thor hit the Mind Stone with his lightning, and became known as the Vision.
Vision, declaring that he "was on the side of life", was worthy to lift Mjolnir. Using the Mind Stone mounted in his forehead, he was able to defeat Ultron's army, later defeating Ultron himself and has since joined the Avengers.