Fiatach Finn mac Dáire, a distant descedant of Óengus Tuirmech Temrach, was, according to medieval Irish legend and historical tradition, a king of the Ulaid

Ulaid

The Ulaid or Ulaidh were a people of early Ireland who gave their name to the modern province of Ulster...

, later a High King of Ireland

High King of Ireland

The High Kings of Ireland were sometimes historical and sometimes legendary figures who had, or who are claimed to have had, lordship over the whole of Ireland. Medieval and early modern Irish literature portrays an almost unbroken sequence of High Kings, ruling from Tara over a hierarchy of...

, and the eponymous ancestor of the early Medieval

Early Medieval Ireland 800–1166

The History of Ireland 800–1169 covers the period in the history of Ireland from the first Viking raids to the Norman invasion. The first two centuries of this period are characterised by Viking raids and the subsequent Norse settlements along the coast...

 Ulster

Ulster

Ulster is one of the four provinces of Ireland, located in the north of the island. In ancient Ireland, it was one of the fifths ruled by a "king of over-kings" . Following the Norman invasion of Ireland, the ancient kingdoms were shired into a number of counties for administrative and judicial...

 dynasty of the Dál Fiatach

Dál Fiatach

The Dál Fiatach were a group of related dynasties located in eastern Ulster in the Early Christian and Early Medieval periods of the history of Ireland.-Description:...

. He was king of the Ulaid while Feradach Finnfechtnach

Feradach Finnfechtnach

Feradach Finnfechtnach , son of Crimthann Nia Náir, was, according to medieval Irish legend and historical tradition, a High King of Ireland...

 was High King, and succeeded to the High Kingship himself when Feradach died. He ruled for three years until he was killed by Fíachu Finnolach. The Lebor Gabála Érenn

Lebor Gabála Érenn

Lebor Gabála Érenn is the Middle Irish title of a loose collection of poems and prose narratives recounting the mythical origins and history of the Irish from the creation of the world down to the Middle Ages...

synchronises his reign with that of the Roman emperor

Roman Emperor

The Roman emperor was the ruler of the Roman State during the imperial period . The Romans had no single term for the office although at any given time, a given title was associated with the emperor...

 Nerva

Nerva

Nerva , was Roman Emperor from 96 to 98. Nerva became Emperor at the age of sixty-five, after a lifetime of imperial service under Nero and the rulers of the Flavian dynasty. Under Nero, he was a member of the imperial entourage and played a vital part in exposing the Pisonian conspiracy of 65...

 (AD 96-98). The chronology of Geoffrey Keating

Geoffrey Keating

Seathrún Céitinn, known in English as Geoffrey Keating, was a 17th century Irish Roman Catholic priest, poet and historian. He was born in County Tipperary c. 1569, and died c. 1644...

's Foras Feasa ar Éirinn dates his reign to AD 25-28, that of the Annals of the Four Masters to AD 36-39.

Fiatach Finn mac Dáire was also a cousin of the legendary Cú Roí mac Dáire and Conaire Mór

Conaire Mor

Conaire Mór , son of Eterscél, was, according to medieval Irish legend and historical tradition, a High King of Ireland. His mother was Mess Búachalla, who was either the daughter of Eochu Feidlech and Étaín, or of Eochu Airem and his daughter by Étaín...

 of the Érainn and Dáirine

Dáirine

The Dáirine , later known dynastically as the Corcu Loígde, were the proto-historical rulers of Munster before the rise of the Eóganachta in the 7th century AD. They appear to have derived from the Darini of Ptolemy and to have been related to the Ulaid and Dál Riata of Ulster and Scotland...

 (Clanna Dedad). The Dál Fiatach are said to descend from the "Family of Cú Roí" in the Book of Glendalough (Rawlinson B 502). Descendants of Fiatach Finn and the Dál Fiatach include those with the surnames Haughey

Haughey

Haughey is an Irish surname. Spelling variations include: Hoey, McCaughey and McKeogh, among others. Modern spelling comes from the original Ó hEochaidh.The Haugheys are descendants of the ancient Dál Fiatach dynasty, rulers of the Ulaid...

/Hoey

Hoey

Hoey is an Irish surname. Spelling variations include: Haughey, McCaughey and McKeogh, among others. Modern spelling comes from the original Ó hEochaidh.The Hoeys are descendants of the ancient Dál Fiatach dynasty, rulers of the Ulaid...

, Donlevy/Dunleavy, and MacNulty.