The Avengers was all kinds of successful, earning $1.5 billion (with a b) worldwide this summer. Now, with The Avengers 2 in the works, Andy Park's concept art for the characters from the first film has been released. Check it out (click thumbnails to enlarge):
The concept art was clearly completed after casting Jeremy Renner, Tom Hiddleston, Chris Evans, Chris Hemsworth, Scarlett Johansson, and Cobie Smulders. As you can see, the actors were used as inspiration for the drawings, and most of the illustrations are very close to the final character designs (except for Nick Fury's trench coat).