Gleefully Evil
I think the thing that made Bellatrix Lastrange (or at least Helena Bonham Carter's portrayal of her) so creepy was just how much fun she had being so bad. She was gleefully evil (gleevil?), and took great pleasure in doing awful things. Speaking of great pleasure, this MOC by vitreolum gives me all the good wizarding world feels. It's a lot of cool techniques and style packed into a tiny package. And great evil has never been more cute before I believe.
Original author: Tommy