We all have been speculating as to how Ultron will come to fruition next May when [The Avengers: Age Of Ultron](movie:293035) comes to theaters. Joss Whedon had said he was going to rewrite Ultron's origin leading a lot of people to believe it is Stark who creates Ultron instead of Pym. In light of the synopsis coming out today we can conclude that Stark plays no role in Ultron's creation but rather reviving him if you will. This leads to another question if Tony isn't responsible for Ultrons creation then who is? The answer was in front of our eyes the whole time well most of it.
I believe Hank Pym will be the man who comes to create Ultron for S.H.IE.L.D back in the days of Howard Stark and Peggy Carter. With Hank and Howard teaming up to create a peace keeper after Captain America was lost since the people needed someone to defend them. They created Ultron for this sole purpose but in the process the A.I was being corrupted by H.Y.D.R.A so it turned on them so they decided to disarm the project and leave as it is. I believe they had intended to come back to it and make it better for the future but Hank and S.H.I.E.L.D had a falling out and went their separate ways. Ultron ultimately ended up being forgotten for all those years of course until now though. After Avengers and the falling of S.H.I.E.L.D i believe Stark believes that this peace keeper is his perfect replacement for himself and along Banner get to work on it. They soon discover though that the A.I it once had is pretty old and not up to date to what Stark decides to upload it with his database.
As time progresses though Ultrons incredibly advanced A.I. begins to learn and adapt quicker and stops being a puppet for the Avengers. He soon starts to want to break free and rebel against Tony who he believes to be Howard his original creator. Ultron ultimately turns on the Avengers and hacks through Tony's database to create Ultron clones. In the process he also tampers with J.A.R.V.I.S creating The Vision whose sole purpose is to destroy The Avengers. Thats just my theory on who ultimately creates Ultron which is Hank Pym and Howard Stark but Tony is the one to revitalize him in the future. This could mean Peggy Carter who was there during Ultrons original creation could know the secret to his end? We wont know for sure till the movie comes out next May but what are your predictions let me know comment below!