Rhiainfellt, name variants including Rieinmelt and Rieinmelth, was a British princess of the royal house of the kingdom of Rheged, a part of the Hen Ogledd.
Rhiainfellt is identified in the Historia Brittonum as the wife of Oswiu and the granddaughter of Rhun son of Urien Rheged.
The apparent conflict could be reconciled if Rhun in reality had stood sponsor at the baptism, thus becoming Edwin's godfather.
[7] Whatever the precise political relationship between Rheged and Northumbria, the fact that a Northumbrian prince married a princess of Rheged shows that the British royal house retained high status, and probably political power.
Rhiainfellt's father, 'Royth' (Rhaith - meaning 'Justice' in Welsh), was possibly the last king of an independent Rheged.