Who was Llewellyn the Great?

Llewellyn the Great (in Welsh, Llewellyn Fawr) was a prince of north Wales who united all of Gwynedd. He was born in 1173, probably in either Dolbadarn or Dolwyddelan castle, and died in 1240, of a stroke, in Aberconwy. Llewellyn was married to Joan Plantaganet, the natural daughter of King John of England, with whom he had a son Daffydd. He was also married to a Welshwoman named Tannsgwyl Roch, with whom he had another son, Llewellyn, and a daughter, Helen. He is also thought to have built the castle at Criccieth, on the Llyn Peninsula, around 1230.