4. Scarlet Witch And Quicksilver (Marvel)
Who Is This? The Scarlet Witch and Quicksilver are two mutant superheros (or occasionally villains depending on the storyline), who just happen to be the offspring of Marvel villain Magneto. Despite their obvious ties to the X-Books, Wanda and Peitro Maximoff are usually portrayed in the super group the Avengers, not the X-Men. Because of this odd distinction as both mutants and Avengers, Fox and Marvel have joint ownership of the rights to these characters appearing on film.
Why is this person a better choice than WW? Due to the joint ownership issue, both studios will be featuring these superpowered siblings in upcoming films, creating brand awareness for them to spin off their own movie, but that's not as big a factor in why they deserve a movie as simply who they are. These are the children of one of Marvel's most dastardly villains, the pro-mutant terrorist Magneto, a mass-murderer responsible for all kinds of atrocities and disasters worldwide. Imagine how that must mess with these kids' heads, knowing the same blood that runs through them also runs through public enemy number one; its the perfect set up to create some real drama, and I envision this movie as the least action heavy superhero movie of this lot, and almost just more of a character study of how these two live with that heavy burden each day.
Who should be cast? As with Black Widow we're dealing with established movie characters here as opposed to a new cast. Marvel should definitely handle the duties on this one, as one look at the character designs from the two companies shows that, to no one's surprise, Marvel looks like they know how to handle these characters much better than Fox (a studio with a reputation of not doing justice to their characters). That mean Aaron Taylor-Johnson and Elizabeth Olsen get the nod.