NECA's HeroClix is set to release their Marvel's the Avengers line in 2012, and a product description sent to retailers seemingly gives away the identity of the film's top secret villain. If we are to believe this toy description, Captain America: The First Avenger foe Red Skull (Hugo Weaving) will be the one helping Loki to destroy our team of superheroes this summer.
Here is the product description for the HeroClix line of Marvel's the Avengers miniature figurines.
It should be noted that at the end of Captain America: The First Avenger, Red Skull is transported into another realm, which could very well be Asgard. Its also possible that Red Skull is include in his Marvel's the Avengers line simply because it contains 24 single figures, plus 4 team packs of 3 figures each. That's a lot of characters needed to fill out this particular set of miniatures, and NECA may simply be borrowing characters from other Marvel movies.
Marvel's The Avengers was released May 4th, 2012 and stars Robert Downey Jr., Chris Evans, Mark Ruffalo, Chris Hemsworth, Scarlett Johansson, Jeremy Renner, Tom Hiddleston, Clark Gregg. The film is directed by Joss Whedon.