First creation

The titles of Viscount Clare and Baron Moyarta were conferred on Daniel O'Brien, a younger son of Connor O'Brien, 3rd Earl of Thomond

Connor O'Brien, 3rd Earl of Thomond

Connor O'Brien, 3rd Earl of Thomond , called Groibleach , grandson of Conor O'Brien ; succeeded to the earldom, 1553; his right to the lordship of Thomond was disputed by his uncle, Donnell; confirmed in his possessions by Thomas Radclyffe, 3rd Earl of Sussex in 1558, who proclaimed his uncles...

, on 11 July 1662. These titles were forfeit by the attainder

Attainder

In English criminal law, attainder or attinctura is the metaphorical 'stain' or 'corruption of blood' which arises from being condemned for a serious capital crime . It entails losing not only one's property and hereditary titles, but typically also the right to pass them on to one's heirs...

 of the third Viscount in 1691. However, the title continued to be used by his descendants in France. In 1741 the titular sixth Viscount Clare also succeeded as heir-male to the Earls of Thomond

Earl of Thomond

"Earl of Thomond" was a title in the Peerage of Ireland. It was created twice for the family of Ó Briain. The O'Brien dynasty were an ancient Irish sept native to north Munster....

, and assumed that title as well, though because of his grandfather's attainder the succession was not recognised in Ireland. The claim to the viscounty and the earldom became dormant on the death of the titular seventh Viscount in 1774, and the headship of the O'Brien dynasty passed to the Earls of Inchiquin

Baron Inchiquin

Baron Inchiquin is one of the older titles in the Peerage of Ireland. It was created in 1543 for Murrough O'Brien, Prince of Thomond, who was descended from the great high king Brian Boru)...

.

Second creation

The titles of Viscount Clare and Baron Nugent were conferred on the politician Robert Craggs-Nugent on 19 January 1767. He was later created Earl Nugent

Earl Nugent

Earl Nugent was a title the Peerage of Ireland. It was created on 21 July 1776 for Robert Craggs-Nugent, 1st Viscount Clare, with remainder, failing heirs male of his body, to his son-in-law George Grenville and the heirs male of his body...

. The viscounty became extinct on the death of the grantee in 1788.

Viscounts Clare (1662)

• Daniel O'Brien, 1st Viscount Clare
  Daniel O'Brien, 1st Viscount Clare
  Daniel O'Brien, 1st Viscount Clare was the younger son of Connor O'Brien, 3rd Earl of Thomond and Una O'Brien....
  
   (d. c. 1666)
• Connor O'Brien, 2nd Viscount Clare
  Connor O'Brien, 2nd Viscount Clare
  Connor O'Brien, 2nd Viscount Clare was the son of Daniel O'Brien, 1st Viscount Clare and Lady Catherine FitzGerald, a daughter of Gerald, 14th Earl of Desmond....
  
   (c. 1605 – c. 1670)
• Daniel O'Brien, 3rd Viscount Clare
  Daniel O'Brien, 3rd Viscount Clare
  Daniel O'Brien was the 3rd Viscount Clare.O'Brien was the son of Connor O'Brien, 2nd Viscount Clare and Honora O'Brien, daughter of Daniel O'Brien and Ellen FitzGerald....
  
   (d. c. 1691; attainted in 1691 but the title used by his descendants)
• Daniel O'Brien, 4th Viscount Clare
  Daniel O'Brien, 4th Viscount Clare
  Daniel O'Brien, 4th Viscount Clare was the son of Daniel O'Brien, 3rd Viscount Clareand Philadelphia Lennard. He was commander of a regiment which he conveyed to France where he fought in the Battle of Marsaglia on 4 October 1693 and was mortally wounded. Daniel O'Brien never married and was...
  
  (d. c. 1693)
• Charles O'Brien, 5th Viscount Clare
  Charles O'Brien, 5th Viscount Clare
  Charles O'Brien, 5th Viscount Clare was the son of Daniel O'Brien, 3rd Viscount Clare and Philadelphia Lennard. He married Charlotte Bulkeley, daughter of Henry Bulkeley and Sophia Stuart, on 9 January 1696, at Saint-Germain-en-Laye, France...
  
  (d. 1706)
• Charles O'Brien, 6th Viscount Clare
  Charles O'Brien, 6th Viscount Clare
  Charles O'Brien, , 6th Viscount Clare was a Irish military officer in French service.Charles O'Brien was the son of Charles O'Brien, 5th Viscount Clare and Charlotte Bulkeley...
  
  (1699 – 1761; titular 9th Earl of Thomond from 1741)
• Charles O'Brien, 7th Viscount Clare
  Charles O'Brien, 7th Viscount Clare
  Charles O'Brien was the 7th Viscount Clare was born in 1757 in Paris,France, the son of Charles O'Brien, 6th Viscount Clare and Marie Genevieve Louise Gauthier.O'Brien died unmarried on 29 December 1774 in Paris, France....
  
  , 10th Earl of Thomond (1757 – 1774)

Viscount Clare (1767)

• Robert Craggs-Nugent, 1st Viscount Clare (1702 – 1788; created Earl Nugent in 1776)

Sources

• http://www.leighrayment.com/peers/peersC4.htm
• http://www.thepeerage.com/p21696.htm
• http://www.thepeerage.com/p19500.htm
• http://www.thepeerage.com/p21696.htm
• http://geneweb.inria.fr/roglo?lang=en;m=N;v=o+brien
• http://web.genealogie.free.fr/Les_militaires/France/Les_senechaux_connetables_marechaux_et_amiraux_servant_la_France_avant_1789.htm