King of Gwynedd 825-844
There appears to have been a civil war in Gwynedd during the early 9th century as two rival kings, Cynan ap Rhodri and Hywel struggled for control of the kingdom. Hywel eventually dominated by the year 816 and ruled until his death in 825. He left no heir and it would seem that Merfyn Frych was invited to take over the vacant throne. (Or, as is quite likely, he invited himself.)
It is recorded that this Merfyn Frych (Frych being the 'Freckled');
a) was the son of Gwriad, the king of Ynys Manaw or the Isle of Man and Essyllt, the daughter of Cynan ap Rhodri, who himself was descended from the main line of the kings of Gwynedd going back to the days of Maelgwyn and,
b) married Nest, the daughter of Cadell ap Brochfael, the king of Powys.
Neither of these things are probably true and are most likely the invention of later propogandists for Merfyn's descendents keen to promote a) the legitimacy of their rule and b) their claim to dominion over Powys.
In contrast to the turmoil of the past Merfyn brought stability and a new vigour to the kingdom of Gwynedd. On his accession to the throne, Gwynedd only consisted of Ynys Mon (that is Anglesey) and probably Arfon but Merfyn managed to re-establish the traditional borders of the kingdom. By the time of his death he was able to pass on a stable foundation to his son Rhodri Fawr, and establish a new line of kings that were to provide Gwynedd with its rulers for the next couple of centuries.
Sourced from A Biographical Dictionary of Dark Age Britain by Ann Williams, Alfred P. Smyth and D. P. Kirby (Seaby 1991)
and the The Welsh Kings by Kari Maund (Tempus 2000)