AVENGERS: AGE OF ULTRON opens today and brings with it one of the biggest villains in Marvel's library: Ultron. But, there are still countless classic bad guys that Marvel can bring into their Cinematic Universe that they have not even touched on yet. We know that Thanos looms big on the horizon, but here is our ranking of ten other great comic book foes that could be great additions to the MCU. If your favorite didn't make the list, feel free to add it to the talk backs below.
Check out the Gallery for the Top 10!
Courtesy of Joblo.com