This is Remus Lupin. He is played by 2 people. David Thewlis and James Utechin. David played in Harry Potter and the Prisoner of Azkaban. James Utechin played in Harry Potter and the Order of the Phoenix, and Harry Potter and the Deathly Hallows pt1 and pt2. In Harry's 3rd year he was the Defense Against the Dark Arts teacher. He was the one who taught Harry to do a Patronus Charm. He is 1 of the best DATDA teacher Harry ever had! At every full moon he changes into a Werewolf. Snape makes the Wolfbane Potion, so when he is a Werewolf he dose not hurt anyone. He got bit from Grayback when he was a very little boy.