Cenydd (in modern Welsh Cennydd; in modern English Kenneth; in French Kinède) was a Welsh hermit saint who traditionally lived in the 6th century.

According to the unreliable Iolo Morganwg, he was one of the sons of Gildas. He married and had a son before entering Llanilltud Fawr as a monk under Saint Illtud. More reliable tradition suggests he was the founder of the church of Llangennith on the Gower Peninsula in Glamorgan and later travelled to Brittany, where his cultus was centred around Languidic. He also had a chapel at Ploumelin.

Legend
Cenydd's rather unusual legend was collected in truncated form by John Capgrave from various Welsh sources, and may be found in the Nova Legenda Angliae. According to this, the saint was a Breton prince, the son of King 'Dihoc' (presumably Deroch II of Domnonée) born of incest apparently at Loughor in Glamorgan while his father attended King Arthur. As an unwanted cripple, Cenydd was placed in a cradle made of osiers and cast into the River Loughor. He was washed out to sea, eventually landing on 'Ynys Weryn' or Worm's Head Island. Here, the local seagulls and a series of angelic interventions, involving a miraculous breast-shaped bell, ensured that he survived and was educated as a Christian. He became a hermit, his only companion being an untrustworthy servant, whose dishonesty was revealed when he stole a spear from one of a group of robbers who had been hospitably received by his master. Saint David later cured Cenydd of his deformity while travelling to the Synod of Brefi in 545. The hermit, however, preferred to remain as he was born and prayed for his previous condition to be restored. The story breaks off abruptly at this point.

Historicity and veneration
Evidence from liturgical calendars and Welsh place-name evidence both suggest the historical existence of Cenydd. His legend, however, appears to be pure fabrication. His feast day is 1 August. William Worcester also records the feast of his translation, apparently to somewhere in North Wales, on 27 June.