Coming out in 2012, The Avengers is a culmination of all the recent super hero movies the past few years. You'll have Robert Downey Jr. as Iron Man, Chris Evans as Captain America, Scarlett Johannsen as The Black Widow, Jeremy Renner as Hawkeye, Chris Hemsworth as Thor, Samuel L. Jackson as Nick Fury, Mark Ruffalo as Bruce Banner, and Lou Ferigno as the voice of The Hulk, taking on Tom Hiddleston as Loki, the central villain to the movie. The rumors are that The Avengers are taking on Loki as he quests for the Cosmic Cube. Further rumors are of an appearance of the Mad Titan, Thanos as HE quests for the Infinity Gauntlet, which was also seen in Odin's Hall of Weapons in the movie Thor, though that may be just a small cameo role to set up for The Avengers 2.
We all know RDJ has done a great job as Iron Man, I have no doubt Chris Evans will be great as Captain America, and I thoroughly enjoyed Chris Hemsworth and Tom Hiddleston as Thor and Loki in Thor. Scarlett Johannsen did great as Natasha Romanoff, aka the Black Widow, and Jeremy Renner had a decent role as Clint Barton, aka Hawkeye in Thor. The wildcard here will be Mark Fuffalo as Bruce Banner. I really enjoyed Ed Norton as Banner. It will be cool having Ferigno as the voice of the Hulk though!