Donell Dubh Ó Cathail

Ó Cathail was the son of a Cormac Ó Cathail, and a nephew or close relative of the Donell Óge Ó Cathail, harper to Elizabeth I. Apparently, harping was the family profession. The family were attached to the family of Viscount Buttevant, Lord Barry or Barrymore.

The family may not have been native to County Cork, as Ó Cathail is the name of unrelated families which originated separately in Galway, Clare, Kerry, Tipperary and Ulster.

His wife was Ellen (alive 1664), daughter of Charles MacCarthy and a granddaughter of Richard Barry of Ballinaltig. His known children were:

• David Óg (1586–1604), who had a son, David fitz David Ó Cathail, born 10 March 1605. The child's mother was Ellis, daughter of Richard, Lord Poer.
• James (died 1609)
• Ellen, married Garret fitz John Barry of Leamlara; their descendants were still extant in the 1900s.
• Lodowick, fl. 1621-c.1654.
• Daniel Óge, fl. 1635–1663.
• Richard, fl. 1637.
• Michael, a minor in the 1650s, alive in the 1690s.

• Cornelius O'Brien (piper) (fl. 1656), bagpiper
• Ruaidri Dáll Ó Catháin (fl. late 16th/early 17th century), harper and composer
• Donnchadh Ó Hámsaigh (1695–1807), Irish harper

• Seán Donnelly: "Daniel Duff O'Cahill (c.1580-c.1660), The Queen's Harper", in Journal of the Cork Historical and Archaeological Society, vol. 105 (2000), pp. 1–26.
• Ann Buckley: "Music and Musicians in Medieval Irish Society", in Early Music, vol. 23 no. 2 (May 2000), pp. 165–190.
• Ann Buckley: "Music in Ireland to c.1500", in A New History of Ireland, vol. 1, ed. by Dáibhí Ó Cróinín (Oxford, 2005) pp. 744–813.