WandaVision

Start date: January 15, 2021
What it’s about: After losing Vision to Thanos, a grieving Wanda creates an alternate reality where she and Vision live together, only for it to slowly come apart.
Major new characters introduced (but not killed): Agatha Harkness, older Monica Rambeau, Quicksilver/Ralph, Billy and Tommy, White Vision.
Major new concepts introduced: The Scarlet Witch. The idea that Wanda is able to create and control so much. Her ability to… sort of create life? Also, the idea of actual magic in the MCU and the first tease of the eventual X-Men in Quicksilver.
Analysis: Being as it was the first story told in Phase Four, many of WandaVisions’ stories and characters have already continued—most notably in Doctor Strange in the Multiverse of Madness—while others, such as Monica, Agatha, and the alternate Vision, have projects of their own on the way. Basically, more than anything else on this list, WandaVision is the show that has seen the most continuation and payoff in its story.
Running Total: In this slot, we’re going to keep a running total of new, major characters now on the table for the future MCU. We disqualify anyone who dies in the story, and if they’re been previously revealed. So, going by the list above, six.