Gabrán mac Domangairt King of Dál Riata ^{1 2}

   Another name for Gabrán was Gabran "the Treacherous" King of Dál Riata.

  Research Notes:

From Ancestral Roots, line 170-4:
"He and his son are both called, in Welsh sources, 'the Treacherous.' Welsh pedigrees make him a son of Dyfnwal Hen, allegedly of the line of Ceretic Guletic, regarded by later Welsh writers as an important ruler in northern Britain. According to Welsh sources, his wife was Lleian, dau. of Brychan, the ruler who gave his name to Brecknock."
--------
From Wikipedia - Gabrán mac Domangairt :

Gabrán mac Domangairt was king of Dál Riata in the middle of the 6th century. He is the eponymous ancestor of the Cenél nGabraín.
The historical evidence for Gabrán is limited to the notice of his death in the Irish annals . It is possible that his death should be linked to a migration or flight from Bridei mac Maelchon , but this may be no more than coincidence.[1]

Cenél nGabraín
Gabrán's chief importance is as the presumed ancestor of the Cenél nGabraín,[2] a kingroup which dominated the kingship of Dál Riata until the late 7th century and continued to provide kings thereafter. Kings of Alba and of Scotland traced their descent through Gabrán to his grandfather Fergus Mór , who was seen as the ultimate founder of the royal house as late as the 16th and 17th centuries, long after the Gaelic origins of the kingdom had ceased to have any real meaning.

Unlike the Cenél Loairn , the Senchus Fer n-Alban does not list any kindreds within the Cenél nGabraín. However, probable descendants of Gabrán, such as Dúnchad mac Conaing and his many kinsmen, would appear to have disputed the succession with the descendants of Eochaid Buide grandson of Gabrán, so that this absence of explicit segments in the kindred may be misleading.[3] A genealogy of David I of Scotland in the Book of Ballymote notes the following divisions:

After Áedán mac Gabráin , between the main line, called "the sons of Eochaid Buide " and "the children of Cináed mac Ailpín ", and the "sons of Conaing"
After Eochaid Buide, between the main line and the "children of Fergus Goll" and the "children of Connad Cerr ... or the men of Fife "
After Eochaid mac Domangairt , between the main line and the Cenél Comgaill

The domain of the Cenél nGabraín appears to have been centred in Kintyre and Knapdale and may have included Arran , Jura and Gigha . The title king of Kintyre is used of a number of presumed kings of the Cenél nGabrain. Two probable royal sites are known, Dunadd , which lies at the northern edge of their presumed lands, and Aberte (or Dún Aberte), which is very likely the later Dunaverty on the headland beside Southend, Kintyre .
Kilmartin may have been an important early Christian site by reason of its proximity to Dunadd and its dedication to Saint Martin of Tours , as may Kilmichael Glassary . However, there appears to be no religious site of the importance of Lismore in the lands of the rival Cenél Loairn.

Notes
^ See under Bridei mac Maelchon .
^ See Sharpe's discussion of Ioan mac Domnaill mac Gabráin, note 258 to Adomnán's Life; the presumption that the Cenél nGabráin takes its name from Gabrán mac Domangairt is no more than that.
^ Sharpe, "The thriving of Dalriada", argues for the unimportance of such segments.

Gabrán married Lleian verch Brychan.