May I note that this list does not include the returns of MCU cast members in "What If...?". Now, coming across this list, you may think of someone like Tim Roth (The Incredible Hulk) or Ben Mendelsohn (Captain Marvel). These are not in the list, because *SPOILERS*, Kevin Fiege has announced the return of these actors in this video: https://youtu.be/Bs2ij2L8f9E
Also, Gemma Chan and Michelle Yeoh have portrayed two characters in the MCU. This is why they are not on the list. Now, when you come across Andrew Garfield in the list, because of his upcomming appearance in "Spider-Man: No Way Home", and you wonder "Where's Tobey Maguire then?", this is because on IMDB pages, Maguire has been announced to be appearing in "Doctor Strange In The Multiverse of Madness". Anyway, that's all I've got to say :)
