Tydfil of Merthyr

Saint Tydfil (Welsh Tudful) was, according to legend, a daughter of King Brychan of Brycheiniog and died a martyr around 480 in the Welsh town that bears her name, Merthyr Tydfil. Her feast is on 23 August.

The sources about her are traditional. Legend counts her as the twenty-⁠third daughter of King Brychan, by his fourth wife. Tydfil was killed, together with her brother Rhun, at Merthyr Tydfil by pagans, either Welsh or Anglo-⁠Saxon (other writers speak of Picts or Saxons), and was buried there. The town's name keeps her memory, for "merthyr" means martyr in Welsh.

The old parish church of Saint Tydfil in Merthyr Tydfil is dedicated to her and is said to stand on the site of her death. Her holy well, Ffynnon Dydfil, thought to have been near the southern end of Well Street in the town, has left no trace. A daughter church of Saint Tydfil's Well stands in the district called "The Quar". The church of Saint Tydfil at Llysworney in the Vale of Glamorgan is also dedicated to her, as was a chapel in Llantwit Major church until it was given to Tewkesbury Abbey.