In the world of Marvel comics, Ultron is an incredibly powerful supervillain. Originating as a robot that has been programmed with human brain patterns, the character becomes sentient and is able to get more and more power as it constantly upgrades itself, making it better, smarter and stronger. He's so powerful, in fact, that Joss Whedon has actually had to downgrade his abilities for the upcoming The Avengers: Age of Ultron.
Before all of you start experiencing epic amounts of nerd rage, however, it should be noted that the writer/director has some very good reasons behind his alterations to the character. Speaking with Entertainment Weekly, Whedon revealed that in writing the 2015 sequel part of the challenge of approaching Ultron was in both finding the strange pain in the robot's psyche and making sure that science-fiction didn't overstep into the world of magic. Said the director the magazine,
"I knew right away what I wanted to do with him. He’s always trying to destroy the Avengers, goddamn it, he’s got a bee in his bonnet. He’s not a happy guy, which means he’s an interesting guy. He’s got pain. And the way that manifests is not going to be standard robot stuff. So we’ll take away some of those powers because at some point everybody becomes magic, and I already have someone [a new character, Scarlet Witch] who’s a witch."
While Whedon seems to be open about talking about Ultron's personality, it's the character's Marvel Cinematic Universe origin story that's currently being kept a closely guarded secret. In the comics the robot was created by Hank Pym a.k.a. Ant-Man, but Whedon has promised that the superhero won't be appearing in the live-action movies until director Edgar Wright's solo movie about the superhero, which is set to come out in November 2015. This has led fans to speculate that it will be Robert Downey Jr.'s Tony Stark a.k.a. Iron Man - The Avengers' resident tinkerer - will be the one who invents the supervillain in The Avengers: Age of Ultron, but we probably won't be hearing any kind of confirmation on that front any time soon.
Personally, I'm thrilled that the folks behind the Marvel Cinematic Universe aren't using the original comics as biblical text. As someone who has been reading superhero stories for his entire life, I don't have any interest in seeing carbon copy versions of old plots, as that's guaranteed to eliminate any kind of surprise elements in the movies and completely smother filmmakers' creativity. As long as they remain true to the spirit and personalities of the characters - as they've been doing for the last five years - then I'll walk away a satisfied fan.
The Avengers: Age of Ultron is currently in pre-production and there are plans to have cameras rolling at the start of next year. The film is scheduled to hit theaters on May 1, 2015.