House: Hufflepuff, 6th Year
Triwizard Tournament: Hogwarts Champion
Cedric Diggory might be what Harry would be like if Harry didn't have a Grand Destiny to face Voldemort sooner or later. He's handsome, brave, loyal, and kind. He believes in fair play. He's the Seeker for Hufflepuff's Quidditch team. And he's dating Cho Chang, a fifth-year and Harry's current crush. When Harry falls from his broom during third year thanks to a Dementor attack, Cedric catches the Snitch, giving Harry the only Quidditch defeat he's had so far at Hogwarts. Cedric and Harry seem pretty evenly matched.
Because they're decent guys, even though they're competing with each other, Cedric and Harry go back and forth helping each other with the different Triwizard tasks. Harry starts it off by telling Cedric about the dragons in the first task. Cedric is a bit suspicious to start with – "Why are you telling me?" (20.35) – because he seems to buy some of Harry's bad press about being a glory-seeker. But, Cedric quickly comes around.
When Harry is struggling with the golden egg clue for the second task, Cedric is the one who suggests that Harry take the egg into the prefects' bathroom and think about it while in water. Without this assistance, we think it would never have dawned on Harry that the second task involved merpeople (certainly never occurred to us).
This trend of mutual cooperation ends with their decision to share the Triwizard Cup in the third task. Harry saves Cedric from a bewitched Viktor Krum (who casts the Cruciatus Curse on Cedric). Harry also tells Cedric to watch out for the giant spider. Because of Harry's help, Cedric refuses to take the Triwizard Cup by himself, even though, in doing so, he's "walking away from the sort of glory Hufflepuff House hadn't had in centuries" (31.239). Harry suggests that they share the Cup: "It's still a Hogwarts victory" (31.244). They take the Cup at the same time, and they're both transported to the Little Hangleton graveyard. There, Harry hears, "Kill the spare" (32.16), and Cedric is suddenly dead.
Even though Cedric is kind and noble, all he is to Voldemort is "the spare." It's obscene to hear Voldemort's complete lack of respect for Cedric's life, especially after all we've seen of his decency as a character. As Professor Dumbledore says at the Leaving Feast, Cedric is "a good and loyal friend, a hard worker, he valued fair play" (37.47). Yet, Voldemort kills him without a second thought. Cedric's sudden death is strategic on J.K. Rowling's part, since this scene underlines the horror of Voldemort's senseless brutality. It also shows how much darker and more serious the remaining books will be, as Voldemort really gets going on his reign of terror.