Clemenza

“Remember, if the time should come when you have to make a choice between what is right and what is easy, remember what happened to a boy who was good, and kind, and brave, because he strayed across the path of Lord Voldemort. Remember Cedric Diggory.”
― J.K. Rowling, Harry Potter and the Goblet of Fire

“Do you remember me telling you we are practicing non-verbal spells, Potter?"
"Yes," said Harry stiffly.
"Yes, sir."
"There's no need to call me "sir" Professor."
The words had escaped him before he knew what he was saying.”
― J.K. Rowling, Harry Potter and the Half-Blood Prince

“Death's got an Invisibility Cloak?" Harry interrupted again.
"So he can sneak up on people," said Ron. "Sometimes he gets bored of running at them, flapping his arms and shrieking...”
― J.K. Rowling, Harry Potter and the Deathly Hallows

“Wit beyond measure is man’s greatest treasure.”
― J.K. Rowling, Harry Potter and the Order of the Phoenix