This is actually a really difficult question, so I'm just gonna go with one of my favourites.
Ever since the last book, one of my new favourites became severus snape, because he had so much more depth than anyone thought.
at first you just think he is cruel towards harry because of his father;
but then you learn about how he loved Lily Evans more than anything in the world, and would do anything to serve her last wishes and protect harry.
And after all 7 books where it goes back and forth between looking like he is on Voldemort's side, and looking like he is on the good side,
you found out that yeah, he isn't the nicest person, but he actually has so much compassion.
It's funny how in all the books I wished he would get killed, but I cried when it actually happened.
Another character I love, I get a lot of raised eyebrows for-
I think I grew a soft spot for her mainly because of Helena Bonham Carter,
but beside from that, she is an amazing criminal!
She's basically Voldemort's only supporter that is on his side, no matter what, and would die for him, (which she did).
And she is so ruthless, most criminals have motives for why they act the way they do, like their past or something that happened,
but she is just downright evil and enjoys every second of it.
She really is a great villain.
drea riot!well behaved women rarely make history.