O'Shaughnessy

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O'Shaughnessy Ó Seachnasaigh
Parent house	Connachta (Uí Fiachrach Aidhne)
Country	Kingdom of Connacht
Place of origin	Irish Gaels
Founder	Seachnasach mac Donnchadh
Final ruler	Diarmaid Ó Seachnasaigh
Titles	King of Connacht King of Uí Fiachrach Aidhne Lord of Cenél Áeda na hEchtge Baron Shaughnessy

Ó Seachnasaigh, O'Shaughnessy, collectively Uí Sheachnasaigh, clan name Cinél nAedha na hEchtghe, is a family surname of Irish origin. The name is found primarily in County Galway and County Limerick. Their name derives from Seachnasach mac Donnchadh, a 10th-century member of the Uí Fiachrach Aidhne, which the Ó Seachnasaigh were the senior clan of. The town of Gort, Ireland, was the main residence of the family since at least the time of their ancestor, King Guaire Aidne mac Colmáin.