Piffl Vhext is a former Jedi who was saved by Count Dooku prior to the Clone Wars and when the war started, she sided with the Separatist movement. The scar across her face is from a battle with her late ex-master, whom she ended up killing just after the injury was received. She is often referred to as "The Ghost", or the "White Assassin" due to the fact that most of her clothes are white, as well as being rather pale in complexion.
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Based on this old drawing.
http://www.furaffinity.net/view/1147514/