Bryn Owain Glyndŵr

Owain ap Gruffudd Fychan was born in or before 1359, the son of Gruffudd Fychan and Elen ferch Tomas. Owain's father's family descended from another, earlier Gruffudd Fychan, younger brother of Llywelyn Fychan, the last lord of Northern Powys, killed alongside Llywelyn ap Gruffudd in the last stage of the Edwardian Conquest of Wales, and ultimately from Madog ap Maredudd, last ruler of a united Powys.

Owain continued in the service of the Fitzalan earls of Arundel following the end of his education. The earl whom his father had served died in 1377, and was succeeded by his son, also named Richard. Owain's service to the younger Richard Fitzalan is one of the most well-attested periods of his career prior to his rebellion. Before the first records of his service to Arundel, however, Owain appears to have been married to Margaret Hanmer, daughter of David Hanmer. The date of this marriage is disputed.

Owain's father-in-law David Hanmer died in early summer 1387, and by July, Owain had returned to settle the family affairs, just as Arundel began to take action against Robert de Vere, the earl of Oxford and Richard II's favourite. He does not appear to have taken part in any further campaigns under Arundel, as though Owain was enrolled in the earl's retinue at the head of his esquires with the aim of serving in France in 1388, his name was crossed out in the lists, meaning he did not serve.