Bartemius "Barty" Crouch Jr. is one of Lord Voldemort's most loyal followers and a major antagonist in the Harry Potter book series. He is the main antagonist of the fourth book Harry Potter and the Goblet of Fire and it's film adaptation of the same name. He orchestrated the events of the book, ensuring that Harry is one of the champions at Hogwarts to lure him to the Little Hangleton Graveyard and use his blood to bring Lord Voldemort back to life, posing as Alastor "Mad-Ey." Moody.
He was portrayed by David Tennant in the film adaptation of Harry Potter and the Goblet of Fire.