Inspirational Dark Lords

In High School I had this math teacher who was scary as hell- He wore black on test days and laughed a cruel chuckle if you answered a question incorrectly. He had glimmering, dark eyes and a balding head that made him look like he was more brains than face. To this day I think of him as one of my great inspirations as a teacher.

What about you, have any scary or dark inspirations somewhere in your past?