A boggart is a shape-shifting creature that takes on the form of the viewer's worst fear. When facing a boggart, it is best to have someone else along, to try to confuse it. Because of their shape-shifting ability, no one knows what a boggart looks like when it is alone.

The charm that combats a boggart is Riddikulus. The charm requires a strong mind and good concentration. The incantation and wand movement alone will not affect a boggart. The correct way to perform the charm is to push past the fear, and concentrate on something that will make the boggart look amusing. The charm does not, in fact, repel a Boggart; it just forces it to assume a shape that the caster will find comical, inspiring laughter, which will defeat a boggart.

Boggarts are particularly fond of inhabiting certain places that are dark, such as in wardrobes, the gap beneath beds, and the cupboards under sinks and desks. On at least one occasion, a boggart was found hiding in a grandfather clock.