It has been reported that the villain for next year’s release of The Avengers has been confirmed as Loki, who will feature in this year’s Thor starring Chris Hemsworth and Tom Hiddlestone. The reports suggest that Loki will acquire the Cosmic Cube and invade Earth with a Skrull army.
Marvel Studios President Kevin Feige said the following:
In my opinion, The Skrulls are really the only viable threat that would require so many superheroes to fight as a team. Sure, you could have The Hulk as a villain in the beginning, but then they have to come together for an even bigger threat.
How this will all play out over the next few movies is yet to be confirmed but as we find out more we will keep you posted.