The title of Baron Inchiquin is one of the older titles in the Peerage of Ireland, dating to 1543. From 1654 to 1855 the Barons Inchiquin also held the titles of Earl of Inchiquin and Baron O'Brien, and was Marquess of Thomond from 1800 to 1855. In 1855, however, those titles became extinct. In the Gaelic nobility, the Baron continues to hold the titles of The O'Brien, Prince of Thomond and Chief of the Name of O'Brien.

Barons of Inchiquin (1543)

• Murrough O'Brien, 1st Baron Inchiquin (d. 1551)
• Dermod O'Brien, 2nd Baron Inchiquin (d. 1557)
• Murrough McDermot O'Brien, 3rd Baron Inchiquin (1550-1574)
• Murrough O'Brien, 4th Baron Inchiquin (1563-1597)
• Dermod O'Brien, 5th Baron Inchiquin (1594-1624)
• Murrough O'Brien, 1st Earl of Inchiquin, 6th Baron Inchiquin (1618-1674)
• William O'Brien, 2nd Earl of Inchiquin, 7th Baron Inchiquin (1640-1692)
• William O'Brien, 3rd Earl of Inchiquin, 8th Baron Inchiquin (1662-1719)
• William O'Brien, 4th Earl of Inchiquin, 9th Baron Inchiquin (1700-1777)
• William O'Brien, 1st Marquess of Thomond, 5th Earl of Inchiquin, 10th Baron Inchiquin (1726-1808)
• William O'Brien, 2nd Marquess of Thomond, 6th Earl of Inchiquin, 11th Baron Inchiquin (1765-1846), elected a Representative Peer in 1816
• James O'Brien, 3rd Marquess of Thomond, 7th Earl of Inchiquin, 12th Baron Inchiquin (1768-1855)
• Lucius O'Brien, 13th Baron Inchiquin (1800-1872), elected a Representative Peer in 1863
• Edward Donough O'Brien, 14th Baron Inchiquin (1839-1900), elected a Representative Peer in 1873
• Lucius William O'Brien, 15th Baron Inchiquin (1864-1929), elected a Representative Peer in 1900
• Donough Edward Foster O'Brien, 16th Baron Inchiquin (1897-1968)
• Phaedrig Lucius Ambrose O'Brien, 17th Baron Inchiquin (1900-1982)
• Conor Myles John O'Brien, 18th Baron Inchiquin (b. 1943)

Heiress Apparent: Hon. Slaney Alexandra Anne O'Brien (b. 1989)