Gruffydd ap Llewellyn (died 1063)

King of Gwynedd. He had gained control of Gwynedd and Powys by 1039, Deheubarth by 1044, and extended his influence to Gwent by 1055. By the middle of the 11th century, most of Wales was either under his direct control or subject to his wishes, but his successors were unable to retain this dominance after his death. He conducted a series of raids across the English border and formed alliances with dissatisfied elements in Mercia and other English border areas. The English moved against him and defeated him at Rhuddlan in 1063, and he was killed by his own supporters.