One of Arthurís three Counselor Knights, found in the Welsh Triads and other Welsh texts. He was the son of Clydno.

While young, arrogant, and in search of adventure, Cynon entered a strange earldom and was directed to an enchanted fountain. Performing a certain ritual at the fountain caused a hailstorm so strong it could kill anyone caught outside, and brought the lord of the region to the fountain to do battle with the brash warrior who had dared to cause the storm. Cynon performed the ritual, and was defeated by the ruler in combat. When he returned to Arthurís court, his tale, inspired Owain to set out in search of the same adventure. (This role is taken by Calogrenat in other versions.)

The early Scottish poem Y Gododdin places Cynon at the Battle of Catraeth around 600 and lists him as one of the few survivors. A Triad says he fell in love with Uriens' daughter Morfudd, Owain's twin sister. A Welsh poem puts his grave at Llanbadarn.

See also
Gwawrddur | The Legend of King Arthur