Harry Potter was secretly and unintentionally a Divination Prodigy. While he did get bad marks, several of his predictions came true in a few of the books.

In Gof, when Ron and Harry are making up answers for their Divination homework, they unintentionally make predictions that come true. For example, Harry said that he would be in danger of burns. Not too long after, he has to face the Hungarian Horntail in the Triwizard Tournament. He predicts that he'll also get stabbed in the back by somebody he thought was a friend, and technically, that does come true. Ron stops talking to Harry after he gets his name pulled out of the Goblet of Fire which is like being stabbed in the back.

Some may argue that Ron had equally prodigious skill in Divination, but here's where Harry made a legitimate prediction: In PoA, during the Divination exam, Harry sees a hippogriff in the crystal ball. Trelawney says he might be seeing the results of the execution that's taking place later that day. Harry says that it appears the hippogriff is flying away. Trelawney, being the almost complete fraud that she is, thinks that the hippogriff's actions are false and dismisses Harry, feeling a bit disappointed in his work. 

Later, Buckbeack the hippogriff does fly away and ends up escaping his execution proving Harry's prediction from earlier true. Rowling spent the whole book showing how ridiculous Divination was and showing us what a fraud Trelawney was so that we would disregard every little and large prediction thinking them false. 

While Trelawney did make a few legit predictions (e.g the prophecies) most of her work was pathetic and Harry was glad to drop the subject after his fifth year, though I do wonder how the HBP would have ended up like if he didn't drop the subject.