The O Flahertys were the biggest property owners in the Aran islands for along time, and there seat of power was Kilmurvey house in Kilmurvy Inishmore, which is still a thriving guest house, The family are now known as the Flaherty Johnstons, as the doyenne Brigid (Nee Kyne from Claregalway who was the district nurse)who died last year married twice. The family still own the heritage cetre at the cliffs of moher etc.. Of course there are other Flaherties but this would be a good place to start.
The O flaherty Clan were from Connemara and owned vast tracts of land there from which they harassed the English forces. many of their castles are still standing in and about connemara. The west Gate of of Galway city bore the legend 'From the ferocious O Flaherties good Lord deliver us,