This name comes from Nuall, which means a nobleman, and is a name that goes back to the mists of early Irish history. It is numerous in all provinces, but especially in Connacht and south-east Leinster. It is especially connected with Co Carlow. The head of the family was the Prince of Foharta (now known as Forth), in Co Carlow.

Among the famous holders of the name was Brian O'Nolan (1911-1966), who was born in Strabane, Co Tyrone but was educated and lived for the rest of his life in Dublin. A senior civil servant by day, he wrote the satirical Cruiskeen Lawn column for The Irish Times and a number of books, including The Third Policeman, The Dalkey Archive and At Swim-Two Birds. He wrote under the names of Flann O'Brien and Myles na gCopaleen. Another distinguished member of the clan was Sir Robert Sidney Nolan (1917-92), the Australian painter, born to Irish immigrant parents in Melbourne.