The Gallagher (Irish: Ó Gallchobhair) family of County Donegal, formerly one of the leading clans of Cenél Conaill, and therefore of all Ulster, originated in the 10th century as a derivative of their progenitor Gallchobhar mac Rorcain, senior-most descendant of Conall Gulban, son of Niall Mór Noigíallach (Niall of the Nine Hostages). The O'Gallaghers held the High Kingship of Ireland during the early medieval period. They also held the rank of hereditary Marshal of the Kingdom of Tyrconnell, ruled by their kinsmen the O'Donnells, from the 14th until the early 17th century.