Did Vision kill Ultron at the end of original six Avengers got help in stopping Ultron, though, as the sequel introduced Vision, Scarlet Witch, and Quicksilver to the Marvel Cinematic Universe. Vision was set to be the final body for Ultron, but the Avengers turned him into a hero instead.
The events of Avengers: Age of Ultron built to a final confrontation between the Avengers and Ultron in Sokovia. Ultron planned to unleash an extinction-level event for humanity by dropping Sokovia from the sky, and he had an army of bots at his disposal to keep the Avengers occupied. This proved to be a futile effort as the Avengers defeated Ultron, evacuated the civilians on Sokovia, and blew up the city before it hit the ground. One of their final goals of the mission was to make sure all Ultron bots were destroyed so he could not return in the future. Vision led the charge in finishing them off, leading to a confrontation with one of the bots.
Vision's interaction with the Ultron bot featured the new Avenger talking to its creator and their differing views on humanity. This ends with the last Ultron bot lunging towards Vision, but Avengers: Age of Ultron cuts away from showing exactly what happens. Instead, the next shot is illuminated with the Mind Stone's power at work. There is no question that Vision defeated the final Ultron bot, but did he kill Ultron altogether"
As long as Vision's ethical and moral stances didn't change over the course of 24 hours, it raises a question about what actually transpired between him and the final Ultron bot. Vision's hesitancy to kill or take life (even artificial ones) points to him not killing Ultron at the end. In his mind, though, there is a distinction between killing and destroying Ultron. That could point us in the right direction of what he ultimately did with Ultron. The power of the Mind Stone is vast and has not been fully explained in the MCU, but it is possible that Vision managed to use it to destroy Ultron without killing him. Perhaps the only way to defeat Ultron without killing him was to absorb him into the Mind Stone itself.
The MCU may eventually address what happened here to clarify Ultron's fate and possible future. Ultron would return in WandaVision. There are plenty of other Ultron-centric stories from the comics the MCU could tell. And since Vision was set up not to have a desire to kill Ultron, the ending of Avengers: Age of Ultron could be another loose end that Marvel Studios pays off years later.
