Like Harry, Minerva McGonagall seems to have hit her stride in Order of the Phoenix.
“Why didn’t you send us a letter by owl? I believe you have an owl?” Professor McGonagall said coldly to Harry.
Harry gaped at her. Now she said it, that seemed the obvious thing to have done.
“I – I didn’t think –”
“That,” said Professor McGonagall, “is obvious.”
“Really, Severus,” said Professor McGonagall sharply. “I see no reason to stop the boy playing Quidditch. This cat wasn’t hit over the head with a broomstick.”
“You look in excellent health to me, Potter, so you will excuse me if I don’t let you off homework today. I assure you that if you do die, you need not hand it in.”
Professor McGonagall poked a large spoon into the nearest tureen. “Tripe, Sybil?”
“But one does not parade the fact that one is All-Knowing. I frequently act as though I am not possessed of the Inner Eye, so as not to make others nervous.”
“That explains a great deal,” said Professor McGonagall tartly.
“Didn’t you listen to Dolores Umbridge’s speech at the start of term feast, Potter?”
“Yeah,” said Harry.
“Yeah… she said… progress will be prohibited or… well, it meant that… that the Ministry of Magic is trying to interfere at Hogwarts.”
“Well, I’m glad you listen to Hermione Granger at any rate,” she said, pointing him out of her office.
“I was just wondering, Professor, whether you received my note telling you of the date and time of your inspec–”
“Obviously I received it, or I would have asked you what you are going in my classroom,” said Professor McGonagall.
“I wonder,” said Professor McGonagall in cold fury, turning on Professor Umbridge, “how you expect to gain an idea of my usual teaching methods if you continue to interrupt me? You see, I do not generally permit people to talk when I am talking.”
“Very well,” [Umbridge] said, “you will receive the results of your inspection in ten days’ time.”
“I can hardly wait,” said Professor McGonagall, in a coldly indifferent voice,
“I should have made my meaning plainer,” said Professor McGonagall, turning at last to look Umbridge directly in the eyes. “He has achieved high marks in all Defence Against the Dark Arts tests set by a competent teacher.”
“Well, usually when a person shakes their head,” said McGonagall coldly, “they mean “‘no’”. So unless Miss Edgecombe is using a form of sign-language as yet unknown to humans –”
“Dear, dear,” said Professor McGonagall sardonically, as one of the dragons soared around her classroom, emitting loud bangs and exhaling flame. “Miss Brown, would you mind running along to the Headmistress and informing her that we have an escape firework in our classroom?”
"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.”
“Our headmaster is taking a short break,“ said Professor McGonagall, pointing at the Snape-shaped hole in the window.