I don't know if this has been mentioned before, but Golbat from Pokémon R/B/Y has gotta be one of the worst-looking sprites that they've ever made. Its eyes looks as if they're about to be vanished into thin air, and its face expression makes me think that it's in horrible pain. D:
I absolutely adore the shiny Umbreon sprite, by the way! The blue stripes look much better on it than the yellow stripes. Plus, it doesn't have the scary-looking red eyes anymore.