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.

Autor: J.K. Rowling