Ultron made perfect sense as the villain of the second Avengers film. One of the team's most pronounced and dangerous foes from the comics, the Marvel Cinematic Universe version of the character was a charismatic and engaging threat who managed to push the Avengers to the breaking point and set in motion the events that would lead to Captain America: Civil War.
The character was seemingly destroyed once and for all at the end of Avengers: Age of Ultron, but what if there is more to his destruction than anyone realized? What if, like the Red Skull before him, Ultron actually survived in some form within the Mind Stone? Could he, or perhaps an aspect of him, reappear in the upcoming Avengers: Endgame?
A Possibility Not Without Precedent
One of the things that made Ultron such a threat in Age of Ultron was his ability to use an entire army of bodies under his command. He could jump between them at will, and couldn't effectively be killed unless he had all the digital and physical copies of himself destroyed. While Vision managed to disconnect Ultron from the internet and the assembled Avengers destroyed all the physical bodies, one almost managed to almost escape. But the last Ultron was cornered by Vision, and seemingly destroyed in a flash of light from a blast by the heroic android.
Ultron isn't the first enemy of the Avengers to be apparently killed by an Infinity Stone, of course. A similar fate befell Red Skull during the events of the Phase 1 film, Captain America: The First Avenger. After finally claiming the Space Stone (then still known as the Tesseract), the Red Skull disappeared in a pillar of blue light. The character was all but considered dead until the events of Avengers: Infinity War, which revealed the former HYDRA commander had been in fact teleported to Vormir, home of the Soul Stone. Turned into the Stonekeeper, Red Skull was forced to serve the Stones after trying to abuse them for his own gain.
The fate of Red Skull proves that the Stones do serve a higher purpose... or even masters... and can change their bearers. The Red Skull we meet in Avengers: Infinity War was a shell of his former self, a humbled and quiet figure standing in strong contrast to the previously boisterous and proud commander.
Much like Red Skull, Ultron spent most of his MCU film trying to use an Infinity Stone as his secret weapon. While Red Skull was spirited away by the very Space Stone he tried to steal, Ultron was seemingly disintegrated by the Mind Stone that he'd intended to bond with. We say seemingly because, unlike even the Red Skull, who we saw nearly reduced to ash before vanishing, Ultron was never given an on-screen death.
As the last of his bodies lunges at Vision, the scene cuts to an explosion of power, the bodies of the two synthetic beings obscured among the energy and surrounding forest. That alone gives at least a shadow of a doubt that he could have survived, absorbed back into the mind stone from which he was born. Some fans have already speculated that Thanos' eventual downfall could be because Vision's consciousness continues to exist in the Gauntlet after his stone was ripped from his skull and placed within it by Thanos. If that is true, and Ultron was, knowingly or not, absorbed into the stone, Vision may not be in there alone.
Avengers: Endgame has a lot of ground to cover, even if the film does run over three hours like the directors of the film have indicated. All the elements that have been teased so far, like the Quantum Realm and the fate of Thanos, are going to take up most of the film, so it would be surprising to see Ultron reappear. But then, no one expected to see Red Skull making a reappearance in Avengers: Infinity War either. Perhaps he too has been rehabilitated after merging with the Vision, giving him the necessary force of will to break free and save the universe.
Admittedly, it's a long shot... but stranger things have happened, especially in the MCU.
Directed by Joe and Anthony Russo, Avengers: Endgame stars Robert Downey Jr., Josh Brolin, Mark Ruffalo, Tom Hiddleston, Chris Evans, Chris Hemsworth, Jeremy Renner, Chris Pratt, Elizabeth Olsen, Chadwick Boseman, Sebastian Stan, Benedict Cumberbatch, Paul Bettany, Samuel L. Jackson, Cobie Smulders, Benedict Wong, Zoe Saldana, Karen Gillan, Vin Diesel, Dave Bautista, Pom Klementieff, Scarlett Johansson, Tom Holland and Anthony Mackie. The film arrives on Apr. 26.