Donough O'Brien, 2nd Earl of Thomond (died 1553), also known as "the fat", was the son of Connor O'Brien, King of Thomond

Connor O'Brien, King of Thomond

Connor O'Brien, King of Thomond was the second to last King of Thomond.Connor was the eldest surviving son of Turlogh-Donn inaugurated King of Thomond in 1498 , and Raghnait, daughter of John MacNamara chief of the MacNamara clan.In 1528, on the death of his father Connor was inaugurated King of...

 and Annabell Burke.

O'Brien married Helen Butler, daughter of Piers Butler, 8th Earl of Ormonde

Piers Butler, 8th Earl of Ormonde

Piers Butler, 8th Earl of Ormond and 1st Earl of Ossory , also known as Red Piers, was from the Polestown branch of the Butler family of Ireland.-Claims to the title:...

 and Lady Margaret Fitzgerald

Margaret Fitzgerald, Countess of Ormond

Margaret FitzGerald, Countess of Ormond, Countess of Ossory was an Irish noblewoman and a member of the powerful and celebrated FitzGerald dynasty also known as "The Geraldines"...

. Donough O'Brien died on 1 April 1553, after being attacked by his brothers at the family seat of Clonroad. His brother Donald O'Brian was named king of Thomond

Thomond

Thomond The region of Ireland associated with the name Thomond is County Clare, County Limerick and north County Tipperary; effectively most of north Munster. The name is used by a variety of establishments and organisations located in , or associated with the region...

 by the Dalgais, but Donough O'Brien's son, 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...

, allied himself with the English and regained control of his lands.

Children of Donough O'Brien, 1st Earl of Thomond and Helen Butler:

• Margaret O'Brien d. 1568
• 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...
  
   b. c 1535, d. 1581

He also fathered an illegitimate daughter, Mary O'Brien, who married Theobald Burke, son of William Burke, 1st Baron Burke of Connell.

Further reading