Sén-Brian Ó Dubhda (died 1354) was King of Ui Fiachrach Muaidhe.
626–627) of Leabhar na nGenealach, Dubhaltach Mac Fhirbhisigh writes of the fate of the hereditary proprietors of Ui Fiachrach.
Although he did capture it, I think that many of the same chieftains did not get hold of much of their native territories since then, for the family, grandsons, and great-grandsons of Sein-Bhrian divided the land among themselves, though they do not possess it today and only a very small portion of the aforesaid chieftains still survive."
The Annals of the Four Masters record his presence at the Second Battle of Athenry (Brian O'Dowda, Lord of Hy-Fiachrach).
Araile do fhlathaibh Ua nDubhda says of him: This biography of a member of an Irish royal house is a stub.