Chieftain and layman. Proposed marriage to Saint Gladys, the daughter of Brychan of Brecknock. When Brychan refused, he kidnapped her, and the two started a violent life on the run. Father of Saint Cadoc of Llancarvan who eventually convinced Gwynllyw and Gladys to give up their violent ways, and follow a religious calling. Monk at Newport, Monmouthshire, Wales. Late in life he became a hermit in rural Wales. An Anglican cathedral is dedicated to him in Newport, Gwent, Wales.
- Book of Saints, by the Monks of Ramsgate
- Lives of the Saints, by Father Alban Butler
- Our Sunday Visitor’s Encyclopedia of Saints
- “Saint Gwynllyw“. Saints.SQPN.com. 27 July 2013. Web. 9 December 2013. <>