Llewelyn Bren, or Llewelyn ap Gruffudd ap Rhys, was a Welsh nobleman of Senghenydd who led a revolt in Wales against King Edward II, in 1316. This was one of the last serious revolts of the Welsh against their English (Norman) rulers. His seven sons took part in the revolt too.
When Gilbert de Clare, Lord of Glamorgan, died at the battle of Bannockburn in 1314, it left a power vacuum. The various people who took over treated the Welsh very badly, at a time when they were already suffering with a famine. Llewelyn appealed to the king, but the king accused him of treason, and he rose in revolt, attacking Caerphilly Castle.
Unable to capture the castle, Llewelyn and his men started a seige. They burned the town and slaughtered some of the inhabitants. As the revolt spread, Kenfig and Llantrisant castles were sacked and many other castles attacked. Towns like Cardiff were raided and buildings burned throughout Glamorgan and Gwent. The king called on Humphrey de Bohun, Earl of Hereford and Lord of Brecon, to put down the uprising. He gathered troops from a wide area, and the support of Thomas, Earl of Lancaster and Roger Mortimer. (These three figure large in the story of Alina and the rebellion of her husband in 1320 in my book Alina: The White Lady of Oystermouth).
The forces were so overwhelming that Llewelyn surrendered to Hereford and begged that his followers not be punished, taking all the blame on himself. This earned the respect of Hereford and Mortimer, who pleaded his case with the king. Most of his followers were indeed pardoned, and Hereford and Mortimer promised to intercede with the king on his behalf.
He was sent with his family to the Tower of London, but then became a prisoner of Hugh le Despenser the Younger, the king's favourite and rapacious land-grabber. In 1317 he had become the Lord of Glamorgan and the largest land owner in the Welsh Marches. Without consulting the king, Despenser moved Llewelyn to Cardiff Castle and had him hung, drawn and quartered without trial. He also imprisoned Llewelyn's wife Lleucu and some of her sons in Cardiff Castle.
Despenser's treatment of Llewelyn enraged both the Welsh and Marcher Lords, who joined together to petition the king against Despenser. When the heir to the Lordship of Gower rebelled against the king, the other Lords joined him. The rebellion which followed managed to free Llewelyn's family and get Despenser and his father exiled, until the king was able to raise a large enough force to counter-attack and put the rebellion down.
However, when the queen and Roger Mortimer landed in 1326 with an army of mercenaries the king, unable to command the loyalty of the barons, fled to Despenser's lands in Wales. There they were understandably unable to raise any forces and were captured. Despenser suffered the same fate he had inflicted on Llewelyn and was hung, drawn and quartered. One of the charges against him at his trial was the murder of Llewelyn Bren. Lleucu and her sons had their estates restored to them.