Barty Crouch Jr.

'''Barty Crouch, Jr. (gone undercover as Dark Wizard hunter Alastor "Mad-Eye" Moody') is a Dark Wizard and an infamous Death Eater, and the true main antagonist in the fourth Harry Potter book/film, Harry Potter and the Goblet of Fire.'' Crouch spends most of the story posing as the friendly teacher Alastor "Mad-Eye" Moody, and became the Defense Against the Dark Arts (D.A.D.A.) teacher at Hogwarts School for Witchcraft and Wizardry during the Triwizard Tournament, hosted by Hogwarts. He was sent byVoldemort, the most-powerful of all Dark Wizards and leader of the Death Eaters, to rig the Triwizard Tournament so that Harry Potter wins the tournament and use his blood to give Voldemort a new body.