Nicholas Hoult has joined the cast of HBO's 'Harry Potter' series in a key role for season two. Hoult will play Professor Gilderoy Lokckhart, who comes to Hogwarts in Harry's second year as the new Defense Against the Dark Arts teacher. Lockhart is a key character in 'Harry Potter and the Chamber of Secrets,' the second book in the series and the source material for season two of the show.
