Boggart

A boggart is a magical creature that, upon being seen, shifts into the shape that represents the viewer's deepest fear. This has caused the fact that no-one really knows how a boggart really looks.

Boggarts are often found in dark places like wardrobes or the space between the bed and the floor. They are most likely the reason for children believing that there are monsters hiding in these places.

The appearance of a boggart in the series first showed up in the book Return of Sauron; Lone Traveller, as Freedom accompanied Remus Lupin during his lessons at Hogwarts. As she had never learned how to defeat a boggart, Remus gave her private lessons with the one he had used for his third-grade students. Freedom's boggart then showed to be a dementor and Remus acknowledged that Freedom really feared fear itself, just like her friend Harry Potter.

Boggarts were later mentioned to have been found in the Four Nations and all of the Queens had succesfully managed to drive them away. A boggart is forced away using the spell Riddikulus.