In Harry Potter and the Prisoner of Azkaban, Cedric Diggory (Hufflepuff seeker) beat Harry Potter when Harry fell off his broom during a Dementor attack and Cedric caught the Snitch first. This was Harry's first competitive loss as a seeker. Cho Chang (Ravenclaw seeker) and Viktor Krum (Bulgarian seeker) also beat Harry in later books, but Cedric was the first. Malfoy never defeated Harry in a proper match.