Everyone knows who are Dobby and Kreacher, the house elfs. But do you know how they were created? Framestore explained how it was done in FMX 2011, because they were tasked to created them both. They challenged many difficult tasks e.g. the heavy wrinkling around the eyes and eyebrows, some of which were too thick, proving difficult to animate without intersecting.
If you want to know what they still had to focus and how they deal with it, read here: 3dworldmag.com