Every one thought the villain for the sequel of the Avengers would be The Mad Titan known Thanos due to the post credit scene however today and Comic-con Marvel announced the Thanos will not be in Avengers 2 but the true villain will be the heartless, human hating, always evolving, super android, ULTRON!
In case you don't know who Ultron is he was a android created be the founding avenger Ant-Man in hope of creating an AI because he believed it was the next form in human evolution, and he succeeded however Ultron began evolving himself and decide that humanity was worthless and decided to dispose of them. Every time he is defeated he always shows up again even more evolve and even stronger. It was only a matter of time until he becomes to powerful to stop.
Avengers 2: Age of Ultron is due for 2015