Albus Dumbledore is the Hogwarts headmaster who serves for most of Harry Potter’s school years in J.K. Rowling’s series.
Dumbledore is headmaster when Harry arrives at Hogwarts and remains a central authority figure through the early and middle books. He is portrayed as an exceptionally powerful wizard, a mentor to Harry, and a key opponent of Lord Voldemort.
The character’s full name is Albus Percival Wulfric Brian Dumbledore. His past, including his friendship with Gellert Grindelwald and the death of his sister Ariana, becomes increasingly important as the series reveals the costs of his earlier ambitions.
Dumbledore is not headmaster for every event in the series. Dolores Umbridge temporarily controls Hogwarts in the fifth book, and Severus Snape becomes headmaster later. Those changes are part of the school’s political and wartime upheaval.