10. Sentry
One thing that really made the MCU famous was their ability to make a shared universe of films that actually worked. In a case like this, it would be a perfect place to suddenly add Sentry now that they’re basically building the MCU back up from the loss of the Avengers.
If you don’t know The Sentry, that’s fine. That means he lived up to his promise. See, when the Sentry was first introduced into Marvel, none of the other characters knew who he was either but here was a man as strong as Superman rolling in, familiar with everyone’s secret identities and had memories of everything they didn’t remember.
Turns out that the Sentry was TOO powerful. This would be fine if one of his powers didn’t also generate a being of dark energy that is so powerful and terrifying that when The Void attacked the Hulk, they found the Hulk on his knees sobbing. The only way they figured out how to fix this issue was to bring in Doctor Strange to, stop me if you’ve heard this one, make the Sentry and the rest of the world forget who he is.
The thought process was that if The Sentry just acted like a normal guy, his powers wouldn’t activate turning off The Void and saving everyone. Unfortunately, this didn’t happen and The Sentry remembers who he was and turned the country finding his old friends like Wolverine, Hulk, Spider-Man, Captain America, and more and making them remember who he was as well leading to a horrific fight with the Void.
Imagine this in the MCU. In those scenes where multiple heroes have the Sentry just duck in and help briefly. Some characters are like, “Thanks Sentry!” and other characters have no idea who that is. This could all lead into The Sentry film where they finally reveal the secret of who the Sentry is and the next Marvel big bad could be the horrifying Void. He’s perfect for a Marvel big bad.