Aberforth Dumbledore is a character in the Harry Potter series of books. He is the younger brother of Albus Dumbledore, the wise, kind good wizard who is one of the major characters of the books.
As with many characters in the books, Aberforth is referenced and shown briefly earlier in the series before he is actually introduced as a speaking character, which does not occur until the seventh book. Many of the references to him are somewhat comical, such as Albus' first mention of his brother, in the Fourth Book:
"My own brother, Aberforth, was prosecuted for practicing inappropriate charms on a goat. It was all over the papers, but did Aberforth hide? No he did not! He held his head up high and went about business as usual! Of course, I'm not entirely sure he can read, so that may not have been bravery..."
Which seems mostly memorable for the
risque nature of mentioning "inappropriate charms on a goat" then for a mention of Albus' family.
In the last book, however, we finally learn that Aberforth Dumbledore does play a serious role in the books. Aberforth was indeed much less literate and sophisticated than his brother, but also was much less arrogant. When they were young, Albus' arrogance caused a terrible tragedy, that Aberforth never totally forgave him for. Albus overcame his mistake, continuing on his way to being a famous wizard, while Aberforth became the barkeeper of a somewhat shady tavern.
Aberforth is described as looking somewhat like Albus, although not as handsome or charismatic. Although he is somewhat disgruntled and skeptical of his brother's many plots and schemes, he is still loyal to his ideas, and works for the Order of the Phoenix. He used his position as a barkeeper to pass gossip and information to his brother. He also, in the final book, secretly aids and hides the students of Hogwarts who are fighting the Death Eaters.
Aberforth is one more piece of the puzzle that JK Rowling used to construct a story rich in character and texture, that built up from innocuous introductions to complicated endings.