This name is common in all four provinces of Ireland. In Irish, it is Ó Conghaile, which means valorous. Although so widely distributed, the origins of this name are in Co Monaghan and in Connacht.

Among well-known Connollys were William Connolly, the richest man in Ireland in the 18th century. A lawyer and financier, he made his fortune buying and selling land lost by the old Gaelic families exiled after the Battle of the Boyne. He was also Speaker in the Irish Parliament. In 1722, he built Castletown House at Celbridge, Co Kildare, one of Ireland's finest mansions. Restoration is nearly complete and it can be visited.

James Connolly (1870-1916) was one of the leaders of the 1916 Easter Rising and the pioneer of socialism in Ireland. Sybil Connolly, born in 1921, has achieved international fame with her fashion designs; her workrooms are in Merrion Square, Dublin.