In J. R. R. Tolkien's fictional universe of Middle-earth, the Brandybuck clan was a powerful Hobbit family. Like the other main aristocratic families, the Tooks and the Bolgers, they had a Fallohide strain, though they and the Bucklanders among whom they lived were at least partly of Stoor origin, and "by all accounts" had Bree blood as well.
The family began as the Oldbuck clan, who named themselves such apparently after Bucca of the Marish, the first Thain of the Shire. Eleven Oldbuck Thains followed, until Gorhendad Oldbuck crossed into Buckland over the river Brandywine. The Thainship then passed to the Took clan.
Gorhendad took the surname Brandybuck, and began delving the dwelling of Brandy Hall. The village of Bucklebury, and the settlement of Buckland, grew up round the hall.
Buckland technically lay beyond the boundary of the Shire, which was defined by the Brandywine river, and constituted a semi-independent colony ruled by the Master. The Bucklanders were considered 'odd folk' by the other Hobbits of the Shire because they were comfortable with boats and because they locked their doors at night (due to the proximity of the Old Forest). They also preserved words and names of Dunlendish origin, and were regarded by the other Shire Hobbits as having "a feel which we would consider to be 'Celtic'."
The head of the family was the Master of Buckland, one of the officials of the Shire. This office was founded by Gorhendad Brandybuck. Like the Thain and Warden of Westmarch, the Master had only nominal authority, though it extended across the Brandywine into the Marish of the Eastfarthing due to family alliances and the commerce between the two areas.