Saint Gwenfyl was one of the children or descendants of Brychan.
She founded a chapel named Capel Gwenvyl, which no longer exists, subordinate to Llanddewi Brefi in Ceredigion.
[2] She shares a festival on 1 November with her sister, Saint Callwen.
[3] As with Callwen, her name is only mentioned briefly in the Welsh calendars or genealogies.
[4] Callwen and Gwenful were added to the number of children of Brychan in a short list of saints published in the Cambrian Register, but it would be wrong to assume they were more than descendants in some degree.