Niall Glúndub (died 917), his grandson, also King of Ailech and High King of Ireland
They fought a battle against Niall Glúndub in which the Irish were routed, and according to the annals Sitric then "entered Áth Cliath", i.e. Dublin, which we must assume means that he took possession of it.
Niall Quinn | Niall Ferguson | Niall Ó Dónaill | Niall Griffiths | Niall Glúndub | Niall Wright | Niall Lepper | Niall Campbell, 10th Duke of Argyll | Niall O'Dowd | Niall mac Fergal Óge Ó hUicinn | Niall mac Cailein | Niall Lucy | Niall Gunn | Niall Garve O'Donnell | Niall FitzGerald | Niall Caille | Niall Brigant | Brenda Niall |
He was the son of Niall Glúndub and Gormlaith, thus his father and both of his grandfathers—Niall's father Áed Finnliath and Gormlaith's father Flann Sinna—had been High King of Ireland.