"Her lips pulled into a sneer that stole her face of any beauty it might have had; her stony white features were an edifice, like a statue filled with poison. At first glance, her features appeared human in their form, but the longer Obi-Wan looked at her, the more alien she appeared. Her skin was pallid, nearly gray, and all along her face were vein-like markings that made her icy countenance all the more stony. It was as if she were merely the marble likeness of a woman, rather than a being of flesh and blood. Obi-Wan could see her sharp white teeth glinting at him as she stepped towards him, her pale hair fluttering."

Just experimenting with the idea. It's not QUITE right, but I think color will help, as well as more practice.

Evil people are fun to draw...