The Avengers Trailer
I hear tell that while it looks like Loki is the main baddie from the trailer there is a bigger, stronger enemy for the team to face. I’ve heard theories from Skrulls to a Red Skull possessed Hulk as options. Since the Cosmic Cube is mentioned in two of the films, my thought is that it’s possiblely Thanos, Magus, or MODOK (or any of the other villains who wielded it in the comics is an option as the main bad guy.) And don’t forget, Armin Zola made an appearance in Captain America as well as Hydra. But as the first super-team of Marvel Comics, the Avengers have a looooooong, amazing list in the rogues gallery to choose from. Of course, my vote would be for the Masters of Evil, but that’s just wishful thinking.