The Marvel Cinematic Universe might be the biggest brand in the business, but they don't get everything their own way, especially when it comes to the legal minefield of who owns the rights to what characters. Disney had to buy Fox for Marvel to get their hands on the X-Men and Fantastic Four, while Universal are still playing hardball with their ownership of solo movies starring the Hulk, which is why Mark Ruffalo has spent close to a decade as a supporting player.