Cedric Diggory and Harry Potter
EDIT: Cedric Diggory was claimed to be the 'real' Hogwarts champion by Hufflepuffs and Slytherins, because Harry's name should have never been in the Goblet of Fire.
CORRECTING THE ABOVE EDIT :) : Cedric Diggory was the real Hogwarts Champion, not Harry Potter. The Goblet of Fire constitutes a binding contract - according to the Goblet of Fire, Cedric Diggory was the ONLY Hogwarts student drawn. Harry Potter was submitted under the name of a fake school. So according to the rules and laws of the Triwizard Tournament, Cederic Diggory was the only and real Hogwarts champion. - plekkie