My money is going to Lupin (Wormtail has a sterling silver hand, afterall) and McGonagell (I'm sure I butchered her name). Remember when she yelled to Umbridge (paraphrased), "I'll make sure Harry Potter is an auror if it's the last thing I ever do!"
~Or~
Possibly Draco Malfoy-- just because he's such a little wussy mamma's boy.
I thought McGonagal was a goner in #5 when she took 4 stunners to the chest.