Aberforth

There are also clues (the smell of goats) that Dumbledore’s brother Aberforth is that barman.

A Potter Prediction 2005

But you know Aberforth having this strange fondness for goats if you've read book seven, came in really useful to Harry, later on, because a goat, a stag, you know.

Three Player Bridge 2007

Aberforth glared at her: His lips moved as if he were chewing the words he was holding back.

Harry Potter and the Deathly Hallows Rowling, J. K. 2007

But there were any number of things that would seem incredible about Dumbledore; that he had once received bottom marks in a Transfiguration test, for instance or had taken up goat charming like Aberforth …

Harry Potter and the Deathly Hallows Rowling, J. K. 2007

But Aberforth always talked a little madly, poor boy.

Harry Potter and the Deathly Hallows Rowling, J. K. 2007

Oddly enough, there are characters in Book 7 with a material reason to hate Muggles: the Dumbledore brothers, Albus and Aberforth.

The Volokh Conspiracy » Nonideological Evil in the Harry Potter Series: 2007

Also, the locket found in Grimmauld Place and the part with Mundungus and Aberforth where Aberforth clutches his cloak tightly around his neck are a VERY convincing argument.

A Potter Prediction 2005

“Right then,” said Aberforth when the had eaten their fill and Harry and Ron sat slumped dozily in their chairs.

Harry Potter and the Deathly Hallows Rowling, J. K. 2007

Aberforth Dumbledore probably has it now, and he probably has no idea what it is.

A Potter Prediction 2005

He waited for Aberforth to jeer or to argue, but he did not.

Harry Potter and the Deathly Hallows Rowling, J. K. 2007