Cynog ap Brychan

[9] He was murdered on the mountain called the Van (Bannau Brycheiniog) while living with a community of hermits who became jealous of his holiness and resentful of his admonitions against their slothfulness.

He wrote of this relic: Moreover I must not be silent concerning the collar which they call St. Canauc's; for it is most like to gold in weight, nature, and colour; it is in four pieces wrought round, joined together artificially, and clefted as it were in the middle, with a dog's head, the teeth standing outward; it is esteemed by the inhabitants so powerful a relic, that no man dares swear falsely when it is laid before him: it bears the marks of some severe blows, as if made with an iron hammer; for a certain man, as it is said, endeavouring to break the collar for the sake of the gold, experienced the divine vengeance, was deprived of his eyesight, and lingered the remainder of his days in darkness.The detailed description, which, though not easy to interpret, points, in the opinion of Sir T. D. Kendrick, to its probably being Welsh or Irish work of the Viking period, i.e. the 10th or the 11th century.

[11] He is chiefly commemorated in Brycheiniog, where Defynnog, Ystradgynlais, Penderyn, Battle, Llangynog, and Merthyr Cynog, are all named after him, the last being reputed his place of burial.

[11] Saint Cynog is believed to have spent time in Ireland where he was known as Mochonog or Mocheanog (literally meaning mo-chean-og - 'my young Canoc').

A national school in Bray has been named in his honour[14] According to tradition his brother was St. Mochorog or Mo-Goroc[15] who was also active in Wicklow and founded churches at Kilmacurragh, Delgany and Enniskerry.