(6th century), traditionally the parents of Cadoc. Gwynllyw was a chieftain of SE. Wales: Gwladys was one of the twenty-four children of Brychan. Much of their life was given over to armed violence, but their son Cadoc converted them to a devout life. They settled at Stow Hill, near Newport (Gwent), where they lived austerely like monks; but their ascetical practice of cold-water bathing in the Usk, winter and summer alike, preceded and followed at night-time, it appears, by a mile-long walk in the nude, was brought to an end by Cadoc, who persuaded his parents to separate. Gwladys moved eventually to Pencanau in Bassaleg. Gwynllyw was visited on his death-bed by Dyfrig: he died on 29 March. All these details come from a Life dating in its present form from the 12th century: it includes some interesting miracle stories from the times of Edward the Confessor and William I. Several place-names and church dedications in the districts associated with these saints preserve their memory. Feast: (together) 29 March.
From The Oxford Dictionary of Saints in Oxford Reference.