Madog Fychan may have had a claim to be a hereditary Prince of Powys Fadog 1304-ca. 1325. However his very existence is uncertain. It is claimed that he succeeded to his father Madog Crypl's titles on his death in 1304. However, it is more likely that Madog Crypl's son was Gruffydd, who was succeeded by Gruffydd Fychan II, the father of Owain Glyndŵr.
- Sewell genealogy
- Welsh Princes
- J. E. Lloyd, Owen Glendower: Owen Glyn Dŵr (Clarendon Press, Oxford, 1931), 9-17 (not mentioned).