If you were to pick only two evil fictional characters to combine, I don’t think you could do much better than Darth Vader and Skeletor. It may seem like an odd pairing at first, but when you look at this bust created by Ryan Renders, you can see that the two compliment each other quite nicely.
You can see one angle above, but there are a few more below that give you a better sense of the feel of the project. Now, can we make this actually wearable with a full suit of armor? That would be some pretty wicked cosplay action right there.