Muggles' Guide to Harry Potter/Characters/Wilkie Twycross

Overview
Wilkie Twycross is the Apparition instructor from the Ministry of Magic.

Half-Blood Prince
Wilkie Twycross, an oddly insubstantial wizard, starts teaching Apparition to Harry's year group in February. It is a twelve-week course, and the expectation is that at the end of that time, any young Wizard taking the course would be able to pass their Apparition test. The cost of the course is 12 Galleons.

As is only to be expected, as the course progresses, Mr. Twycross is made fun of by many of the wizards taking his course. Ron, in particular, has unkind words for him and his teaching.