For the majority of MCU fans, Disney+'s WandaVision has thoroughly pleased fans. Not only has the show been littered with plenty of Easter eggs and comic book references, but there have also been several allusions to what the future holds for everyone's favorite superheroes. Especially since Elizabeth Olsen teased that there will be "Luke Skywalker-level cameo," (a remark made in reference to the Jedi's shocking appearance at the end of The Mandalorian's second season.)
Intense speculation has already started swirling about who it could be. Which character from the MCU would qualify? Are they even from the MCU? There are lots of possibilities, with some way farther outside of the box than others.
Mark Hamill
Elizabeth Olsen may be having a bit of fun with fans. The Luke Skywalker level cameo could be Luke himself. Mark Hamill, at least. Elizabeth Olsen is an avowed fan of Mark Hamill, so much so she broke down in tears upon meeting him at the premiere for Civil War.
Luke's appearance in The Mandalorian was a great ending for the second season, and his appearance as a new character in the MCU, or one comic book fans might be very familiar with, would be an equally great cameo in WandaVision.
Ultron
A more inside-the-box choice would be Ultron. The villain from Avengers: Age Of Ultron plays an instrumental role in Wanda Maximoff's life, and it's very likely that the major cameo will have some connection to her.
Ultron died at the end of the movie, but fan theories are abound on how he could return. The return of Ultron could spell trouble not just for Wanda but the rest of the MCU and would be a great treat for fans of the franchise.
Thanos
Another possible villain cameo is one that would have a much more immediate impact on Wanda and Vision. It's possible Thanos is the major cameo in the series.
Thanos died twice in the course of Avengers: Infinity War and Endgame, but thanks to Wanda's reality-altering powers and abilities, she may open a door for his return. Thanos is at the heart of Wanda's trauma in the series, thanks to his merciless killing of Vision for the Mind Stone, an act that clearly still haunts her.
Spider-Man
Wanda's story is far from over after WandaVision. She will appear in Doctor Strange In The Multiverse Of Madness, and she may appear in the third Spider-Man movie as well. That makes sense, as the third Spidey movie is clearly going to be dealing with some multiverse weirdness in the form of Doctor Octopus and Electro. But Spider-Man could appear in WandaVision first.
At the end of Far From Home, Peter Parker's secret identity is revealed and he's accused of murdering Mysterio. FBI agent Jimmy Woo came to Westview seeking a missing witness from the witness protection program. Could that be Peter Parker, now in hiding?
Wolverine
Spider-Man would be tremendous, but not be on the level of Luke Skywalker at the end of The Mandalorian season two. With Wanda altering reality, and the MCU seeming to drift into bringing in non-MCU characters, especially in Doctor Strange, the possibilities are endless. One big one is Wolverine.
An appearance by Hugh Jackman as Logan would be exactly the shocking cameo Olsen teases. If WandaVision opens the door to other franchises as some have speculated, this would be the boldest way to go.
Quicksilver (Aaron Taylor-Johnson)
Wolverine doesn't exactly have a strong connection to Wanda or Vision, though, so the possibility remains that it's someone close to her. A major MCU character that fits the bill is her brother, Pietro Maximoff, AKA Quicksilver. Pietro died in Age Of Ultron, but there are many ways how Wanda's twin brother could return.
It's clear that his death still haunts Wanda, evidenced by the anger and hurt she expressed when Monica Rambeau inadvertently brought up the sore subject with her.
Quicksilver (Evan Peters)
A more shocking way of bringing Quicksilver back would be to do it with his Fox X-Men franchise counterpart. Lots of speculation centers around how Wanda could bring the MCU and former Fox franchise together and Quicksilver is the most obvious choice.
Because of that, he might not be the major shock fans expect at this point. But if Peters does appear, as is widely rumored, he might not be playing Quicksilver. Another theory suggests he could be playing Wanda's son, Tommy.
Magneto
A major cameo that would blow fans away from the Fox X-Men movies would be Magneto. Magneto is significant in Wanda and Pietro's life because he is their father. Or, he was in the past. The comics have since retconned this, and rights issues altered their origin in the MCU. WandaVision could be the chance to set it all right.
The only question would be which Magneto it is. Many actors could play Magneto in the MCU, but he's already had two legends play him before. Ian McKellen played him as an older version of the character and Michael Fassbender played the younger Erik Lensheer in the past.
Arnim Zola
The shocking character Olsen is teasing may have actually already appeared in the MCU. Many questions surround Westview, and whether or not there is someone else in control besides Wanda. An MCU villain with a strong connection to TV screens is Arnim Zola, who appeared to perish in The Winter Soldier.
This MCU Phase 1 villain happened to occupy a military base in New Jersey, where Westview is, and in the comics has made a career of seeking new bodies to inhabit, an idea that may or may not have relevance for the synthezoid Vision and his children.
Olsen Twins
WandaVision is built on loving vintage TV references. The show is progressing decade by decade into the present, with the 90s coming up soon. Is the shocking secret cameo from one of the biggest sitcoms of the decade, Full House?
Could Elizabeth Olsen's sisters, Mary-Kate Olsen and Ashley Olsen, who played Michelle Tanner on the hugely popular series, make an appearance in WandaVision? It would be the kind of completely left-field appearance that would rival the shocking return of Luke Skywalker in The Mandalorian.