Ultron is a supervillain appearing in American comic books published by Marvel Comics, most commonly serving as one of the main antagonists of the Avengers franchise, the main antagonist of the Ant-Man series, and a major antagonist in the Iron Man franchise. He has also served as the titular main antagonist of many Marvel storylines, such as Ultron Unlimited, Age of Ultron, and more.
He is a highly delusional robot, who is bent on destroying humanity, in order to replace humans with machines. First appearing in Avengers #54, he has become most recognizable as being one of, otherwise, the most common arch-nemesis of the Avengers, mainly his own creator, Hank Pym the first Ant-Man, as well as Vision. He has alson been an adversary of the Guardians of the Galaxy and Adam Warlock, making him a galactic threat.
He is often seen as being Hank Pym's greatest creation, due to his great power and his goal of saving Earth, but also his worst nightmare as Ultron's means of saving Earth is wiping out all of humanity.
Debuting in the Silver Age of comic books, Ultron has since featured in Marvel products across different media, such as animated television series and video games. Tom Kane and Jim Meskimen are among the actors that have portrayed the character via voice acting. The character appears in the Marvel Cinematic Universe movie Avengers: Age of Ultron (2015), played by actor James Spader, while Ross Maquand voiced alternate universe versions in the Disney+ animated series What If...? (2021) and in the movie Doctor Strange in the Multiverse of Madness (2022).