Ultron is here in the latest What If…? and he could possibly be the new Thanos for the fledgling Guardians of the Multiverse. "What If Thor Was An Only Child" introduced fans to a version of the Avengers villain where he was actually Vision. This reveal comes right at the tail end of the Disney+ adventure. All season long, What If has been hinting at a larger unifying threat, and it seems like Ultron would be a good candidate. Thanos has popped up multiple times over the course of this season and it seems like Marvel has cooled on using the Mad Titan as the main villain for much of anything in Pase 4. Remember just a few months ago when Loki decided to just riff on how inconsequential the Infinity Stones were during its run? This could help signal that as well.