Murrough O'Brien, 1st Earl of Thomond

Murrough O'Brien, King of Thomond
Murrough O'Brien, last King of Thomond & 1st Earl of Thomond
King of Thomond
Reign	1539-1543
Predecessor	Conor O'Brien
Successor	Monarchy abolished Donough O'Brien, 2nd Earl of Thomond
Earl of Thomond
Reign	1 July 1543 - 7 November 1551
Successor	Donough O'Brien
Baron of Inchiquin
Reign	1July 1543 - 7 November 1551
Successor	Dermod O'Brien
Died	7 November 1551
Spouse	Eleanor FitzGerald
Issue	Dermod O'Brien
House	Ua Briain
Father	Turlough O'Brien
Mother	Raghnait MacNamara

Murrough O'Brien, 1st Earl of Thomond (Irish: Murchadh Ó Briain) (died 7 November 1551) was the last King of Thomond, and a descendant of the High King of Ireland, Brian Boru.

A member of the Irish nobility, he was the son of Turlough, King of Thomond and his second wife, Raghnait MacNamara, and also brother of Connor, who was inaugurated King of Thomond in 1528. On his brother's death in 1539 he set aside his nephew Donough and made himself of King of Thomond. He married Eleanor FitzGerald, daughter of Thomas FitzGerald, Knight of the Valley. They had three sons and four daughters.

On 1 July 1543 O'Brien surrendered his Irish royalty to King Henry VIII of England and the same year he was raised to the Peerage of Ireland as Earl of Thomond, with remainder to his nephew Donough (who was created Baron Ibrackan on the same day) and Baron Inchiquin, with remainder to the heirs male of his body. The grant of the English titles was conditional upon the abandonment of native titles, the adoption of English customs and laws, the pledging of allegiance to the English crown, apostasy from the Roman Catholic Church, and conversion to the Anglican Church.

In August of that year he joined the king's Privy Council.