Dumbledore is named after the Early Modern English word for a bumblebee: a dumbledore. The similar word dumbledor may be found in a poem in The Hobbit by J. R. R. Tolkien.
Albus Dumbledore was born during the summer of 1881 in Mould-in-the-Would, England.
He had a difficult childhood in which his sister, Ariana, was attacked and emotionally scarred by a group of boys, and his father, seeking personal justice, retaliated. His father was then sent to prison, where he eventually died.
His mother moved her remaining family to a more accepting community, where they lived a guarded life.
He attended Hogwart's School of Wizardry and Witchcraft. Shortly after his graduation, his plans for a grand tour of the magical world were cut short when a magical outburst from his sister ended up killing his mother.
He befriended Gellert Grindelwald, a young wizard for whom he also presumably held romantic feelings. Grindelwald proved to be a bad influence upon Dumbledore, and when confronted by his brother, Aberforth, the three broke out into an escalated wizard's duel.
When Ariana tried to intervene, she was struck by a fatal curse and died. For the rest of his life, Dumbledore was unsure if it was he who had cast that errant curse.
After the dissolution of his friendship with Grindelwald, he returned to Hogwarts to be a professor, teaching Transfigurations. Slowly, he gained rank at the school, eventually becoming its Headmaster.
A former student of Dumbledore's named Tom Riddle, but operating under the name of Lord Voldemort, later approached Dumbledore, seeking to teach the Defense Against the Dark Arts course. Denied the position, he placed a curse upon the course, resulting in devastation for any future instructor for the course.
Dumbledore oversaw the school during most of Harry Potter's attendance. However, on June 30, 1997, he died at the hands of Severus Snape.
He was entombed on school grounds, buried with the Elder Wand.
After his death, he reappeared to Harry Potter in spirit form and in the form of his animated portraits.