Melkor/Morgoth with the Silmarils
My personal vision of him, after the theft of the Silmarils - the iron crown is heavy, and the light of the Silmarils too bright, but he never puts them away, becoming paranoid about his greatest treasure. In the same time he realizes it, as his expression shows. He is an evil lord, but still has some feelings, and he can sense the doom in the Jewels he is wearing. And yes, he is not ugly. He was described as "Dark Lord, tall and terrible" in the Silmarillion, but terrible does not have to be ugly. It can be the inner power that makes his enemies tremble when they look at him.