I've got an idea for a villain, but I have no idea what he looks like in his regular form (he's a shapeshifter). Here's the basic outline of his powers and motivations:
His name is Doppelganger. He can shapeshift into any humanoid and mimic everything but their DNA patterns. If he grabs on to a superpowered being, he can drain powers from them and use that power himself. He has a detailed knowledge of the underside of society.
A few years ago, Doppelganger's wife was killed by a supervillain. A hero was there, but chose to rush the villain rather than save his wife. Doppelganger has held a hatred of all superpowered beings since then, and wants to punish them by ruining their careers (Rob a store as them, etc.)
Any ideas?