O'Mahony is a surname of Irish origin, derived from the Gaelic name Ó Mathghamhna, which means "descendant of Mathghamhain." The name is commonly associated with the province of Munster in Ireland, particularly in counties like Cork and Limerick. The O'Mahony family has a rich history, often linked to the Eoghanacht dynasty, which ruled parts of Munster. Members of the O'Mahony clan have played significant roles in Irish history, including military and political positions, and the name is still prevalent in modern Ireland and among the Irish diaspora.