Cedric Diggory, a fictional character in the Harry Potter series of novels, was the Hufflepuff Quidditch captain and Seeker through Harry's third year of school. Cedric's father is Amos Diggory, who works at the Ministry of Magic; his girlfriend was Cho Chang. Cedric has been described as "the strong silent type" and "handsome". In Harry Potter and the Goblet of Fire, he will be played by Robert Pattinson .

In Harry's third year, in Harry Potter and the Prisoner of Azkaban, Cedric captained the Hufflepuff team which beat Gryffindor. In Harry Potter and the Goblet of Fire, Cedric was selected to be the Hogwarts champion in the Triwizard Tournament. When Harry is mysteriously selected as well, Draco Malfoy makes Support Cedric Diggory badges for the Slytherins.

Cedric, along with Moaning Myrtle, assists Harry in solving the clue of the second task of the Triwizard Tournament, in return for the help Harry had given him for the first task.

At the end of the third task Cedric refuses to take the cup without Harry, each of them having helped the other through the maze, so they grasp it together. The cup turns out to be a portkey which transports them to Voldemort and his servant Wormtail. Voldemort has Wormtail murder Diggory with the Avada Kedavra curse. Harry escapes, bringing with him Cedric's body in accordance with Cedric's posthumous wish: that he be brought back to his parents.

His wand had a unicorn tail hair in it. It is remarked in Harry Potter and the Philosopher's Stone that "Always the innocent are the first victims." The character, Ronan, was referring to unicorns, but he could also have been foreshadowing Cedric's murder.