From the blue, uh, things from Avatar, to Yoda from Star Wars, this video gives you a rapid fire look at what could have been, if artists' actual sketches were brought straight into the costuming room. Some, like Yoda, came out way better in the films than the sketches, while others, like Whiplash from Iron Man 2 are almost identical. Chewbacca is my favorite change, with the original sketch looking like some kind of 8 foot tall space orangutan, and is not really cool at all. If you looked over to the shotgun seat of the Millennium Falcon and saw that furry horror staring at you, you'd freak the hell out.
Especially if you were in hyperspace.
Credit to Movieclips for the video.