O'Brien (Barony)
A peerage of the Kingdom of Ireland.
Letters patent issued on Wed 21st Oct 1654
To Murrough O'Brien as Hereditary peerage subsidiary to another created by the same letters patent.
Holders
| Number | Surname | Forenames | Held from | Held to |
|---|---|---|---|---|
| 1st | O'Brien | Murrough | Wed 21st Oct 1654 | Sun 9th Sep 1674 |
| 5th | O'Brien | Murrough | Fri 18th Jul 1777 | Wed 10th Feb 1808 |
| 6th | O'Bryen | William | Wed 10th Feb 1808 | Fri 21st Aug 1846 |
| 7th | O'Bryen | James | Fri 21st Aug 1846 | Tue 3rd Jul 1855 |
Peerage extinct on Tue 3rd Jul 1855 with the 7th holder .