Irene

“Hang on . . .” Harry muttered to Ron. “There’s an empty chair at the staff table. . . . Where’s Snape?”
"Maybe he's ill!" said Ron hopefully.
“Maybe he’s left,” said Harry, “because he missed out on the Defense Against the Dark Arts job again!”
“Or he might have been sacked!” said Ron enthusiastically. “I mean, everyone hates him —”
“Or maybe,” said a very cold voice right behind them, “he’s waiting to hear why you two didn’t arrive on the school train.”
Harry spun around. There, his black robes rippling in a cold breeze, stood Severus Snape.”
― J.K. Rowling, Harry Potter and the Chamber of Secrets

“Harry witnessed Professor McGonagall walking right past Peeves who was determinedly loosening a crystal chandelier and could have sworn he heard her tell the poltergeist out of the corner of her mouth, 'It unscrews the other way.”
― J.K. Rowling, Harry Potter and the Order of the Phoenix

“NO!”
The scream was the more terrible because he had never expected or dreamed that Professor McGonagall could make such a sound.”
― J.K. Rowling, Harry Potter and the Deathly Hallows

“All was well.”
― J.K. Rowling, Harry Potter and the Deathly Hallows