I'm a sucker for watching a character visually evolve over time. It's almost like looking at alternate lives that a fictional character could've embodied with slightly different personalities. For example, you can see how Spryo the Dragon seemed to have an entirely different attitude in these early designs.
And though the movie's not quite out yet, you can see how the main character of the video game-centric feature film Wreck-It Ralph started out as more of a monster in this series of images released by Disney. I'm guessing that the prevailing wisdom argued that a more creature-like Ralph would have been harder to be sympathetic to. Who knows? Ralph's final Lil' Abner/Mario look works just fine, but I sure like the different illustrative styles that he journeyed through.