4. Ultron
By now, we should accept that Hank Pym will not be the creator of Ultron. Especially now that 69 year old Michael Douglas has been recently set as the size-changing hero. Theres still a small glimmer of hope that Pym has a hand with the existence of the invincible sentient being, but as of now Pym has no involvement with AoU. If so, the creation of Ultron should be passed down to the next qualified inventor, Tony Stark himself. The Comic-Con trailer has heavily hinted at Tonys involvement with the indestructible android. The trailer begins with the image of Iron Mans helmet; as it plays the helmet slowly transforms into the head of Ultron.
A possible casting call revealed Stark as the creator also. Iron Man 3 vaguely hinted at a potential origin for Ultron. Tony was able to create Iron Man suits without the need of a human pilot. They had both the ability to be remote controlled by him and piloted by an A.I. system. He successfully paved the way for future sentient being. Tony no longer wants to battle crime himself, but he may instead create Ultron to protect the world for him. A second possibility has been in front of our faces since the first Iron Man. Tony may have already set the blueprints for Ultron when he created J.A.R.V.I.S. He is capable of interacting like a living being, possess vast, deep knowledge on many subjects, and has a sarcastic personality programmed into him. In many ways, J.A.R.V.I.S. is already like a person. But as weve seen, the advanced A.I. system can be easily overridden by those with high-level technology. Tony may create a body for J.A.R.V.I.S. only for a hidden villain to modify it in a terrible way. In addition, Captain America: The Winter Soldier's debut trailer reveals the seedy underbelly of S.H.I.E.L.D. Nick Fury utters, We are going to neutralize a lot of threats before they happen. To which Captain America responds, I thought the punishment came after the crime? With this and the reveal that CA: TWS will be vital to Age of Ultron, fans have theorized S.H.I.E.L.D. will call upon Tony to create Ultron as a weapon to end crime and terrorism.