Harry Potter
"But I'm not a teacher, I can't-"
"Harry, you're the best in the year at Defense Against the Dark Arts," said Hermione.
Book/ Year: Order of the Phoenix/ Year 5
Distinguishing Features: This should so be obvious to everyone joining this clique...
Reason for Leaving: He taught the class because the students asked them to- since DJU didn't want to show them anything and the students were frightened of You-Know-Who. But they get caught, and of course they will have a new teacher next year (which hopefully won't be as bad as Umbridge).