- Born: Abt 376
- Marriage: Unknown
Brion, son of Eochaid Mugmedon, older half-brother of Niall Noigiallach (Niall of the Nine Hostages), was one of the three brothers whose descendants were known as the Connachta and who gave their name to the province of Connacht in the west of Ireland. His particular descendants, the Ui Briuin, gave rise to many Kings of Connacht and its ruling families over the next thousand years. A descendant of his via the Ui Briuin Ai was Tairrdelbach Ua Conchobair, who became High King of Ireland in 1166.