Gruffudd ap Llywelyn ( – 5 August 1063) was the only Welsh king to unite all of Wales, ruling from 1055 to 1063. He had previously been King of Gwynedd and Powys from 1039 to 1055. Gruffudd was the son of Llywelyn ap Seisyll, King of Gwynedd, and Angharad, daughter of Maredudd ab Owain, King of Deheubarth, Gruffudd seems to have been able to drive Hywel (and his Irish fleet of "Black Gentiles / Pagans") John of Worcester referred to him, several decades later, as Rex Walensium, 'King of the Welsh'. daughter of Ælfgar, Earl of Mercia after he abducted, and married, the wife (name unknown) of Hywel ab Edwin in 1041.
Gruffudd's granddaughter, Nest ferch Osbern (Nesta of Hereford), married Bernard de Neufmarché, the first Norman Conqueror of Wales, and they became the parents of Countess Sibyl de Neufmarché, mother of Roger FitzMiles, 2nd Earl of Hereford, and grandmother of Humphrey III de Bohun, who married Scottish princess Margaret of Huntingdon, Duchess of Brittany. Gruffudd may have had another son, Owain ap Gruffudd, who died in 1059.