Ieuan Fychan ap Ieuan ap Adda (d. c. 1458 ), poet, and an ancestor of the family associated with Mostyn Hall. Ieuan Fychan lived at Pengwern, Denbs. , before he married Angharad, heiress of Mostyn. Lord Mostyn and T.A. Glenn, in their History of the Family of Mostyn of Mostyn (London, 1925), give some details about the career of Ieuan Fychan; e.g. in 1415 he was an esquire in the retinue of Thomas Fitz Alan, earl of Arundel, and he also fought in France. Ieuan Fychan was a contemporary of the bards Guto’r Glyn and Maredudd ap Rhys, with the latter of whom he had a bardic controversy. For translations of some poems written by or to him see the History mentioned above.

He was, according to the bard Guto’r Glyn, a bard and a harpist.