Albus Dumbledore is a fictional wizard and headmaster of Hogwarts School of Witchcraft and Wizardry from the Harry Potter series of books and movies. The character of Dumbledore was played in the films by Richard Harris until his death in October 25, 2002 caused by Hodgkin's Disease. The role has since been played by Michael Gambon.
Background
Dumbledore was born to Kendra and Percival Dumbledore in July or August, 1881. His mother was killed by his mentally unstable sister Ariana Dumbledore when he was 18 years old. His father went to prison for attacking a muggle (person of non-magic heritage) when he was 10. By the age of 17 he had fallen in love with Gellert Grindelwald but was let down by him after Grindelwald killed his sister showing his true character.
During his long lifetime he enjoyed being the Head Of Gryffindor House; Transfiguration Professor, Headmaster of Hogwarts School of Witchcraft and Wizardry, Order of Merlin First Class, Supreme Mugwump and Chief Warlock of the Wizengamot.
Dumbledore was murdered by Severus Snape after young Draco Malfoy was unable to fulfill his promise to Voldemort kill Dumbledore. He is the only headmaster buried at Hogwarts.
Albus Dumbledore Timeline
The Harry Potter Lexicon: Albus Dumbledore Timeline
1881: Born
1891: Father goes to prison
1892: First year at Hogwarts
1899: Takes N.E.W.T. exams
1938-1955: Transfigurations Professor at Hogwarts
1938: Meets with Tom Riddle
1945: Defeats Grindelwald
1955: Becomes headmaster at Hogwarts
1956: Hires Minerva McGonagall as Transfigurations Professor
1980: Severus Snape warns him about Voldemort's plans to attack James and Lily Potter
November 1, 1981: Leaves baby Harry on the Dursley's doorstep
December 25, 1991: Gives Harry his father's Invisibility Cloak
May 8, 1993: Lucius Malfoy removes him from his Headmaster position
September 1993: Allows Hermione Granger to use a time-turner to attend extra classes
June 1995: Calls together the Order of the Phoenix
Spring 1996: Dolores Umbridge removes him as Headmaster
June 1996: Faces Voldemort at the Battle at the Department of Mysteries
Summer 1996: Obtains the Salazar Slytherin Ring Horcrux
June 1997: Enters Horcrux cave with harry | Severus Snape kills him
May 1998: Speaks with Harry from the after-life one last time