It's nearly impossible to find a movie that hasn't been touched by the magic of visual effects (VFX). Some effects—like extensions of backgrounds—are hardly noticeable. But in other cases, they're front and center. The VFX artist's job, then, is to make something unbelievable look utterly real.
You'd be hard pressed to find a better example of both subtle and not-so-subtle VFX than Industrial Light & Magic's work in The Avengers. The company just released its reel for the film, which shows how that VFX sausage gets made.
The Hulk could have easily looked plastic and fake, but in the capable hands of ILM's animators, he looks believable in all of his angry, green glory. It's no surprise that ILM received an Oscar nomination for its work in the film. According to the company's YouTube page, "This reel represents a small fraction of the work created by over 200 ILM artists, scientists, and engineers backed up by a world class production team."
Even more delightful are the stop-motion animations that open and close the reel, which were created by hand and shot one frame at a time by ILM "stop motion guru" Erik Dillinger.