I had a member of my group who played a Doppleganger who had been cursed and permanently polymorphed into an Elf, and was a Druid simply because he hated being an elf and losing all his shapechanging abilities.
Sure, on paper he wasn't that exciting... he was just an Elf Druid. But he had a pretty screwed up character past.
Even worse was when he struck a deal with demons to partially remove the curse placed upon him... all the animals he shapeshifted into became Fiendish.