Favorite Professor. This is a tough one, because there are a lot of Hogwarts professors that I like, for a lot of really awesome reasons. But there is one that stands out above the rest, and no, it's not Remus. (I do like Remus, and he was definitely the best DADA professor they ever had, but his tenure was short and he made some questionable decisions, so I went in another direction.)
Professor Minerva McGonagall!
This gif is EVERYTHING. McGonagall is sassy, snarky, extremely intelligent, competent, and has a bit of a wild streak, but never has time for anyone's bullshit. I always kind of liked her, but it was her vs. Umbridge in OotP that really solidified her as my favorite. I HATED Umbridge so much that I literally shook with rage while reading that book (this is not an exaggeration) and watching McGonagall take her down calmly and succinctly was possibly the best part of that book.
"My grandmother thinks Charms is a soft option," mumbled Neville.
"Take Charms," said Professor McGonagall, "and I shall drop Augusta a line reminding her that just because she failed her Charms O.W.L., the subject is not necessarily worthless." - HBP
Also, she can turn into a cat, which is by far the best animagus form to have.
Bless you, Minerva, bless.
ETA: Please excuse this (somewhat lengthy) excerpt from one of my favorite scenes from Deathly Hallows, and probably from all of Harry Potter.
“We can push it off on the kids,” said Amycus, his pig like face suddenly crafty. “Yeah, that's what we'll do.... He can punish them. Couple of kids more or less, what's the difference?”
“Only the difference between truth and lies, courage and cowardice,” said Professor McGonagall, who had turned pale. “A difference, in short, which you and your sister seem unable to appreciate. But let me make one thing very clear. You are not going to pass off your many ineptitudes on the students of Hogwarts. I shall not permit it.”
“Excuse me?”
Amycus moved forward until he was offensively close to Professor McGonagall, his face within inches of hers. She refused to back away, but looked down at him as if he were something disgusting she had found stuck to the lavatory seat.
It's not a case of what you'll permit, Minerva McGonagall. Your time's over. It's us what's in charge here now, and you'll back me up or you'll pay the price.”
And he spat in her face.
Harry pulled the Cloak off himself, raised his wand, and said, “You shouldn't have done that.”
As Amycus spun around, Harry shouted, “Crucio!”
The Death Eater was lifted off his feet. He writhed through the air like a drowning man, thrashing and howling in pain, and then, with a crunch and a shattering of glass, he smashed into the front of a bookcase and crumpled, insensible, to the floor. “I see what Bellatrix meant,” said Harry, the blood thundering through his brain. “You need to really mean it.”
“Potter!” whispered Professor McGonagall, clutching her heart. “Potter--- you're here! What---? How---?” She struggled to pull herself together. “Potter, that was foolish!”
“He spat at you,” said Harry.
“Potter, I --- that was very --- gallant of you --- but don't you realize --?”
“Yeah, I do,” Harry assured her.
See? Even Harry knows she's awesome.