O’ Reagan, O’ Regan, O’ Regane, Reagan, Ó Riagáin
Ó Riagáin comes from the Gaelic word “ríodhgach”, possibly meaning ‘impulsive’ or ‘angry’. The name originated in at least three distinct areas of the country ; Meath / Dublin, where they were one of the four tribes of Tara, Thomond in Co. Limerick where they were part of the Dál gCais tribal grouping, and Fermoy in Co. Cork. Today the name is the sixty sixth most numerous in Ireland, and is strongest in the province of Munster.