Gellert Grindelwald is a fictional character from the Harry Potter universe, created by author J.K. Rowling. He is known as one of the most powerful dark wizards in history and is a central figure in the Fantastic Beasts film series. Grindelwald seeks to establish a new world order where wizards rule over non-magical people, believing this will lead to a better society. Grindelwald's character is complex, as he was once a close friend of Albus Dumbledore, sharing dreams of a united magical community. Their friendship ultimately turns into rivalry, leading to a legendary duel between them.