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.
Martin Joseph Blake was an Irish historian who died around 1930.
William O'Shaughnessy, The O'Shaughnessy was an Irish Chief and Major-General.
Ruaidhrí Gilla Dubh Ó Seachnasaigh was an Irish Knight and Chief of the Name. He is known in English as Sir Roger O'Shaughnessy.
Donal IV O'Donovan,, The O'Donovan, of Clancahill, was the son of Donal III O'Donovan, The O'Donovan of Clancahill, and Gyles (Sheela) O'Shaughnessy, daughter of Elis Lynch and Sir Roger Gilla Duff O'Shaughnessy, The O'Shaughnessy.
Sir Roger O'Shaughnessy, The O'Shaughnessy, was Chief of the Name and a captain in the Irish army of James II of England. He was present at the Battle of the Boyne, and died ten days after the battle at his castle in Gort. All his property was declared forfeit, and his son and heir, William O'Shaughnessy, was forced into exile.
Leabhar Ua Maine is an Irish genealogical compilation, created c. 1392–94.
Diarmaid Ó Seachnasaigh, Irish knight and Chief of the Name, died before 1567.
Diarmaid Riabach Ó Seachnasaigh, Chief of the Name, died 1579.
Sir Liam Ó Seachnasaigh was an Irish Chief of the Name.
Sir Dermot Ó Seachnasaigh, Chief of the Name, died 1606. He was a son of Sir Ruaidhrí Gilla Dubh Ó Seachnasaigh and Lady Honora O'Brien, daughter of Murrough O'Brien, 1st Earl of Thomond.
Sir Ruadhri Gilla Dubh Ó Seachnasaigh was Chief of the Name during 1583–1650.
Sir Dermott Ó Seachnasaigh, Chief of the Name, died 1673.
Melaghlin Reagh Ua Seachnasaigh was an Irish Chief of the Name.
Colman O'Shaughnessy, O.P. was an Irish Roman Catholic clergyman who served as Bishop of Ossory from 1736 until his death in 1748.
Robuck or Roebuck O'Shaughnessey was an Irish Chief of the Name and Lord of Cenél Áeda na hEchtge.
Bartholomew O'Shaughnessey, Chief of the Name, born 1789, alive 1843.
Muircheartach mac Pilib Ó Ceallaigh was Archbishop of Tuam in Ireland, and patron of the literary compilation An Leabhar Ua Maine. He was a son of Pilib Ó Ceallaigh, and a brother to William Buidhe Ó Cellaigh, King of Uí Maine and Chief of the Name.
John Ó Seachnasaigh was an Irish Chief of the Name.
Cormac MacDermot MacCarthy, 16th Lord of Muskerry (1552–1616) was an Irish magnate and soldier. He fought at the Siege of Kinsale during Tyrone's Rebellion.
