Gilderoy Lockhart became the Defence Against the Dark Arts Teacher during Harry's 2nd year.
He was originally a Ravenclaw.
He later used his talents to achieve fame, sell books, and boast about how good he was.
He later tries to boast how awesome he was to Harry, and to help Harry on his future "career" of bullshit.
He later gets busted for lying by Harry and Ron, and tries to back-stab them and in return his plan backfires and his memory is wiped.
I liked seeing his return in Order of the Phoenix, recovering at St. Mungos with the mind equal to a child.
