Shlimazel
Shlimazel is a Bogeyman who tries, rather foolishly, to frighten Susan in Biers during the events of Hogfather. Susan has considerable experience with Bogeymen and many other forms of monsters who attack children. She has developed methods of dealing with them, often using blunt instruments, but in this case her Death Voice: 'Go away and stop bothering me.' is sufficient to unseat and unnerve him and send him fleeing.
Annotation
Shlimazel, appropriately enough, is a Roundworld Yiddish word meaning "a very unlucky or inept person who fails at everything".