Dolores Umbridge
Reasoning: The control-freak card. This represents one who is greedy, demanding and obstinate. They block progress and change, needing to maintain the status quo (which they, of course, create and enforce). Dolores Umbridge invades Hogwarts and enforces her own version of order, controlling through frightening and threatening means. She resists anything that is not ordered by her, and hangs onto her little educational decrees and Ministry policy.
In a traditional tarot deck, this is the Four (4) of Pentacles.
Notes
I loathe Umbridge. Beyond loathing. I have a difficult time drawing her for this reason. Nothing I can do seems horrible enough for her (although I think I got pretty close with the hideousness of the colors and decor here....)
This is the one card I've computer edited besides color adjustment: there is a small dark flaw on the paper, right in the middle of one of those froggy, pouchy cheeks. I should be able to fix it when I order a certain pen to block it out, but for now it was distracting so I just computered it out. :B