Both Paul Bettany and Elizabeth Olsen had teased a mysterious guest star appearing on WandaVision, with Olsen going so far as to call it the show's "Luke Skywalker moment," referring to the famous surprise cameo by Mark Hamill in the Season 2 finale of Star Wars: The Mandalorian. Once Evan Peters, who played Quicksilver in the X-Men film series, showed up in Episode 5 of WandaVision as Wanda's brother, Pietro (instead of Aaron Taylor-Johnson, who plaed Pietro in Avengers: Age of Ultron), some fans believed that Peters' appearance was the mysterious guest star.
However, Paul Bettany recently explained that there is a whole other mysterious guest star who will be appearing in a future episode of the series whose presence has yet to be revealed (or leaked, like the rumors of Peters' involvement in WandaVision way back in June of 2020).
Esquire released a video of their "Explain This" video feature by having Paul Bettany react to fan theories about WandaVision and one of the theories was that Benedict Cumberbatch would be making a surprise cameo on the series as Doctor Strange to set up the second Doctor Strange film, Doctor Strange and the Multiverse of Madness. Bettany replied by noting that there were characters that they were trying to keep secret but the information got out there (Peters' Pietro and Teyonah Parris' Monica Rambeau) but, "There is one character that has not been revealed. And it is very exciting. It is an actor that I've longed to work with all of my life and we have some amazing scenes together and the chemistry between us is, I think, extraordinary and it is just fireworks on set. I'm really excited for people to see that stuff."
It is interesting to note that Bettany didn't actually say that Cumberbatch wouldn't be appearing, which could possibly be a very clever dodge on his part. Still, though, that Bettany says that the actor has not yet been revealed obviously proves that it is not Evan Peters as Pietro, so we still have time to guess who might be a big enough surprise to count as the series' "Luke Skywalker moment."
Written by Jac Schaeffer and directed by Matt Shakman, WandaVision stars Elizabeth Olsen as Wanda Maximoff/Scarlet Witch, Paul Bettany as Vision, Randall Park as Agent Jimmy Woo, Kat Dennings as Darcy Lewis, Teyonah Parris as Monica Rambeau and Kathryn Hahn as Agnes. New episodes air Fridays on Disney+.
Source: YouTube