- The Smyths were settled in county Waterford from Elizabethan times. In the 17th century Richard Smyth of Ballynatray, county Waterford, married as his second wife Alice, daughter and co heir of Richard Grice of Ballycullane, county Limerick, and had a son Grice Smyth from whom descend the Smyths of Ballynatray. In the mid 19th century Ballynatray passed by marriage to Charlotte Mary wife of Charles William Moore, who succeded his brother as Earl Mount Cashell. They took the additional name of Smyth. In November 1861 their estate of 1,673 acres in the barony of Coshlea and liberties of Kilmallock, county Limerick (the Grice estate) was advertised for sale. In the 1870s the Honourable C.W.M. Smyth of Ballinatray owned over 7000 acres in county Waterford as well as 272 acres in county Limerick. In the 1890s Ballynatray was inherited by the eldest daughter of Earl Mount Cashell, Lady Harriette Gertrude Isabella Smyth, who had married in 1872 Colonel John Henry Graham Holroyd. They assumed the name of Smyth.
Captain J.R. Smyth who owned 799 acres in county Tipperary and 2 acres in county Dublin in the 1870s may have been a member of this family. His agent was James Cahill of Blenaleim, Carrick on Suir.
- This family appear to have connections with the Smyths of Ballinatray, county Waterford and a late 17th century Francis Smyth of Rathcoursey is mentioned in the Ballyinatray entry in Burke's ''Landed Gentry of Ireland'' (1904). At the time of Griffith's Valuation the Smyths held land in the parishes of Cloyne, Dungourney and Middleton, barony of Imokilly, county Cork. In the 1870s John James Smyth of Rathcoursey owned 866 acres in county Cork. He was the eldest son of John Smyth of Rathcoursey and his wife Mary daughter of William Smyth of Coolbay, county Cork. In 1871 he married Jane daughter of William Mason of Derrylahan, county Tipperary.