Ó Nualláin is an Irish Gaelic surname, the original form of the Anglicized surname Nolan. It derives from the given name Nuallán, which is a diminutive of nuall, meaning "famous" or "loud", combined with a diminutive suffix. Thus, the surname Ó Nualláin signifies "descendant of the famous one" or "descendant of the loud one".
In traditional Irish naming conventions, the prefix Ó (later Anglicized as O') denoted a grandson or male descendant, leading to the patronymic Ó Nualláin. Over time, as Gaelic names were Anglicized under English influence, Ó Nualláin was adapted to Nolan, the form most common today. The surname historically clustered in the province of Connacht, particularly in counties Mayo and Sligo, reflecting the ancient territory of the Uí Fhiachrach, a leading Connacht dynasty.
The root name Nuallán itself appears as a distinct given name, sometimes anglicized as Nullan or Nolan. While the Ó Nualláin surname is less common outside Ireland, its Anglicized counterpart Nolan has spread widely, notably carried by figures such as the baseball legend Nolan Ryan (b. 1947).
- Meaning: Descendant of Nuallán (the famous/loud one)
- Origin: Irish Gaelic
- Type: Occupational/Patronymic Surname
- Usage Regions: Ireland (especially Mayo, Sligo)