Sir Donough O'Brien, 1st Baronet (1642 – 17 November 1717) was an Irish politician and baronet.

He was the son of Connor O'Brien and his wife Mary McMahon. In 1692, O'Brien entered the Irish House of Commons

Irish House of Commons

The Irish House of Commons was the lower house of the Parliament of Ireland, that existed from 1297 until 1800. The upper house was the House of Lords...

, sitting for 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....

 until 1714.

He married firstly Lucia Hamilton, daughter of Sir George Hamilton and had one son named Lucius O'Brien. Lucius was the father of Sir Edward O'Brien, 2nd Baronet

Sir Edward O'Brien, 2nd Baronet

Sir Edward O'Brien, 2nd Baronet was an Irish politician and baronet.He was the son of Lucius O'Brien, son of Sir Donough O'Brien, 1st Baronet, and his wife Catherine Keightly...

. Secondly he married Elizabeth Deane, daughter of Major Joseph Deane

Joseph Deane

Joseph Deane was an Irish politician and judge who became Chief Baron of the Irish Exchequer.- Background :He was born at Crumlin, Dublin, son of Joseph Deane and his wife Elizabeth Parker, daughter of John Parker, Archbishop of Dublin. His grandfather Major Joseph Deane was a close associate of...

 and together they had one son named Henry O'Brien. When Murrough O'Brien, 1st Earl of Inchiquin

Murrough O'Brien, 1st Earl of Inchiquin

Murrough McDermod O'Brien, 1st Earl of Inchiquin and 6th Baron Inchiquin , was known as Murchadh na dTóiteán ....

was captured Lady Inchiquin petitioned for her husband's release but Sir Donough O'Brien wrote that she had no mind to see any of his relations "for his being a papist".