Venom

He is essential, even if just because Marvel has to bring the genuine version of the character to the big screen. And, since the first solo Spider-Man flick is called Homecoming, this has every chance to happen.

Obviously, Venom won’t appear in the first movie. But the symbiote should. And then it is just a matter of time until Eddie Brock becomes the first incarnation of the super villain. For that matter, it would take more than just Spider-Man to take this villain down. And since the Marvel flicks are more successful when more superheroes are featured, I don’t see why the studios wouldn’t dedicate an entire flick just to him.

And I shouldn’t even mention that this opens a host of other possibilities, even for the larger MCU.