Wikipedia
Mawgan and Meugan (also Meigant) (Latin: Mauganus) are names referring to either one or two Brythonic saints who flourished in the 5th or 6th century.
Both names are widely attested in place-names and church dedications, "Mawgan" in Cornwall and Brittany and "Meugan" in Wales, but it is uncertain whether the names refer to one and the same person. The parishes of St Mawgan and Mawgan-in-Meneage in Cornwall derive their names from St Mauganus. There is also a St Machan in West Lothian (Scotland), as shown by the place-name Ecclesmachan, but again this may be a distinct figure.
No hagiographical Life survives for Mawgan or Meugan, but figures bearing Latinised versions of either of these names appear in the Lives of St Cadog and St David. A saint called Maucan or Moucan features in an episode of the late 11th-century Life of Cadog, in which he arbitrates a quarrel between Cadog and Maelgwn, king of Gwynedd. A Life of St David, also of the late 11th century, refers to a monastery of Mawgan (Maucannus).
Later still, Meugan is mentioned in the Welsh genealogical collection known as Bonedd y Saint, which detail the lineages of Welsh saints. The relevant section has been dated to c. 1510.