Bogies are malevolent faeries said to torture children who misbehave.  Bogies often appear as shadowy, black humanoids, but sometimes take the shape of black dogs, tree trunks, or terrifying entities with icy fingers and glowing yellow eyes.  Some stories of bogies say that these frightening fae will steal naughty children off to hell, so the devil himself can torture them; although this is rarer than simply giving the youngsters a fright.  Bogies can be found anywhere it is dark and dank; preferring cellars, attics, cupboards, closets, caves, hollow trees, or even under a misbehaving child's bed.  Similarly to boggarts, bogies will travel with offending families if they attempt to flee, and moving to a new house is not a surefire method for ridding oneself of their presence.

Bogies are closely related to bogles, who are frightening faeries said to perpetrate malicious pranks on much-deserving criminals and ne'er-do-wells.  Unlike bogies, bogles rarely show themselves to their victims, but their presence can be felt by the overwhelming feeling of dread they evoke.  When a bogle does show himself, he appears as a dark, shadowy, thoroughly unpleasant figure; so much the better to terrorize those who have earned his wrath.

Very often different faeries appear practically identical, and only the activities in which they participate--which themselves are very similar--separate them; making it seem likely that they could be the same being simply given a particular name depending on what they're doing, which appears to be the case with bogies and bogles.

So it's perhaps best to behave yourself, regardless of age, or you might run the risk of drawing a bogie or bogle's ire.