Henry O'Brien, Lord Ibrackan or Lord O'Brien (c.1642 – 1 September 1678), styled Hon. Henry O'Brien until 1657, was an Irish nobleman and politician. He was the son of Henry O'Brien, 7th Earl of Thomond

Henry O'Brien, 7th Earl of Thomond

Henry O'Brien, 7th Earl of Thomond PC was an Irish peer, styled Lord Ibrackan from 1639 to 1657.O'Brien was the son of Barnabas O'Brien, 6th Earl of Thomond and Anne Fermor.In 1641, he married his first cousin Anne O'Brien Henry O'Brien, 7th Earl of Thomond PC (Ire) (c.1620 – 2 May 1691) was an...

 and Anne O'Brien.

He married Katherine Stuart, Baroness Clifton, daughter of George Stuart, 9th Seigneur d'Aubigny and Lady Katherine Howard. They had six children (of whom three died young):

• Donough O'Brien, Lord Ibrackan (1663–1682)
• Hon. Henry O'Brien (b. & d. 1665)
• Hon. Charles O'Brien (b. & d. 1666)
• Hon. George O'Brien, died young
• Hon. Mary O'Brien (d. 1683), married John FitzGerald, 18th Earl of Kildare
  John FitzGerald, 18th Earl of Kildare
  John FitzGerald, 18th Earl of Kildare , styled Lord Offaly until 1664, was an Irish peer.-Background:Kildare was the son of Wentworth FitzGerald, 17th Earl of Kildare and Lady Elizabeth, daughter of John Holles, 2nd Earl of Clare...
  
  
• Katherine O'Brien, Baroness Clifton (d. 1706), married Edward Hyde, 3rd Earl of Clarendon
  Edward Hyde, 3rd Earl of Clarendon
  Edward Hyde, 3rd Earl of Clarendon , styled Viscount Cornbury between 1674 and 1709, was Governor of New York and New Jersey between 1701 and 1708, and is perhaps best known for the claims of his cross-dressing while in office.-Career:Born The Hon...
  
  

In 1661, he represented Clare

Clare (Parliament of Ireland constituency)

Clare was a constituency represented in the Irish House of Commons until 1800.-History:In the Patriot Parliament of 1689 summoned by King James II, Clare was represented with two members.-Members of Parliament:* 1583 Sir Turlogh O’Brien, Ennistymon....

 in the Parliament of Ireland

Parliament of Ireland

The Parliament of Ireland was a legislature that existed in Dublin from 1297 until 1800. In its early mediaeval period during the Lordship of Ireland it consisted of either two or three chambers: the House of Commons, elected by a very restricted suffrage, the House of Lords in which the lords...

, and from 1670 until his death in 1678, Northampton

Northampton (UK Parliament constituency)

Northampton was a parliamentary constituency centred on the town of Northampton which existed until 1974.It returned two Members of Parliament to the House of Commons of the Parliament of the United Kingdom until its representation was reduced to one member for the 1918 general election...

. In 1673, he was appointed to the Privy Council of Ireland

Privy Council of Ireland

The Privy Council of Ireland was an institution of the Kingdom of Ireland until 31 December 1800 and of the United Kingdom of Great Britain and Ireland 1801-1922...

. He died of disease while in camp with his regiment in Flanders

Flanders

Flanders is the community of the Flemings but also one of the institutions in Belgium, and a geographical region located in parts of present-day Belgium, France and the Netherlands. "Flanders" can also refer to the northern part of Belgium that contains Brussels, Bruges, Ghent and Antwerp...

. His courtesy title passed to his younger half-brother Henry Horatio O'Brien, Lord Ibrackan.