Darth Dumbledore was a wizard. If you didn't know that you have been living under a rock for most of your miserable life. Go and catch up with popular culture.
Dumbledore was born into his Wizard family at the age of approximately 60. He had a sad childhood, as he had a psyco Jedi as a father who used the Foce all the time as a means to get around while drunk, a strict mother who expected great things from him, he had a sister who had a strange habit of exploding, and a brother with an... Interesting... Relationship with goats. He had few friends, most notably Dogy and Grundelward, an evil wizard who liked drawing triangles, lines and circles. His brother broke his nose when he looked at a got with a smile on his face.
It is rumoured that Dumbledore met Obi-Wan Kenobi when he flew into space for his honeymoon, and that during that meeting Dumbledore decided to become a sith. Not much is known about this however and he has not talked about it ever since.
Later Later Life
Darth Dumbledore was usually a good wizard, but on his bad days he was headmaster of Hogwarts School of Witchcraft and Blasphemy, I mean Wizardry. He was the leader of the Order of the Pheonix and had a great beard. He waved a wooden stick around and shouted spells all the time, proving that he was not as skilled a wizard as Darth Gandalf. He was in fact bitter enemies with Gandalf and they often had mini wars, Hobbit vs Student, until they all died of exhaustion. He enjoyed living life to the fullest while on holidays, and even bought a pensieve to collect his thoughts and relive his holidays. He was somewhat of a hero to Harry Potter and many other impressionable idiots.
Darth Dumbledore was killed by some zombies in an underground lake, and his corpse shot at by a greasy haired man. It was a sad day for many, but a happy day for Darth Voldemort.