Wilkie Twycross

Wilkie Twycross works for the Ministry of Magic and comes up to Hogwarts to teach Apparition to sixth-years who have turned seventeen, or are close enough to it, and want a licence. His lessons run in the Great Hall and turn on what he calls the Three D's, which he repeats often enough that the class has taken against him and worked its way through a long list of names for him. He is oddly colourless to look at, with transparent eyelashes and wispy hair and an insubstantial air, as though a strong gust might carry him off, and Harry Potter wonders whether all the Apparating has something to do with it.