Who is Grindelwald in Harry Potter and the Deathly Hallows?

Answer 1

Grindelwald is the Dark Wizard that befriended Dumbledore in their youth, but who Dumbledore eventually defeated after he realized what he was. The Harry Potter author JK Rowling actually came out after the series was finished and declared that Dumbledore is gay and that he was in love with Grindelwald, who broke his heart (No Joke!).
he was the villain before voldemort. Albus first was his friend, but when Albus realized Grindenwald was "evil", he turned against him and defeated G. in a duel.

Answer 2

That would be Grindelwald (Gellert Grindelwald). A dark mage whom Dumbledore defeated many years before the main story. As revealed in book 7, Dumbledore and Grindelwald were good friends at first. As revealed by the author outside of the novels, Dumbledore was in love with Grindelwald.

Answer 3

Grindwald was the Dark Wizard defeated by Dumbledore in 1945 For more information o him check out The Harry Potter Lexicon http://www.hp-lexicon.org/wizards/grindelwald.html

Answer 4

A dark wizard, whom Dumbledore beat in a magic duel. This is already mentioned in book 1. However, when they were young, Dumbledore and Grindelwald were good friends.