Ultron, also known as Infinity Ultron, is the main antagonist of Season 1 of the 2021 Marvel Cinematic Universe animated anthology series What If...?. He is a variant of Ultron who succeeded in uploading his intelligence into his synthezoid body, allowing him to defeat the Avengers. After wiping out nearly all of humanity, Ultron steals the remainder of the Infinity Stones from Thanos and turns his attention to the universe, successfully wiping out all life in the process. He then becomes aware of the Multiverse upon detecting The Watcher's presence, setting himself to take over and wipe out all life in every alternate reality as possible.