7. Colonel Klaue/Claw
The answer to who Andy Serkis is? It's been long rumoured that Serkis will be playing Klaw, and will reappear in the Black Panther stand-alone as the arch-villain hell-bent on getting his hands on Vibranium. The only sticking point to that is that Klaw is a ridiculous villain; being composed of pure sound is a bit silly even for a comic book movie, so it would make sense that he goes through some sort of development to make him a bit less odd. The answer might be that Marvel amalgamate two similarly named villains: Klaw and Colonel Klaue, an underling of Baron Von Strucker, who obviously appears in Age Of Ultron as the secondary antagonist. The Klaue point isn't just picked out of the air - IMDB have one actor (Bentley Kalu) listed as "Klaue's Mercenary". That would allow for a more seamless integration, and a means to tie Black Panther even closer to the Avengers narrative. Why He'll Appear Again, Vibranium is the big point. It's reasonable to assume that the villain starts off as some sort of underling to Von Strucker with knowledge of the metal that Ultron attempts to exploit, and then perhaps go through whatever impregnates him with powers (to become Klaw) ahead of a second appearance in Black Panther.