James O'Brien, 3rd Marquess of Thomond

The Marquess of Thomond
Born	1769
Died	3 July 1855 Bath, Somerset
Buried	St. Saviour's Church, Walcot, Bath
Allegiance	Great Britain
Service/branch	Royal Navy
Rank	Admiral
Commands	HMS Childers HMS Thisbe HMS Emerald HMS Diadem HMS Warspite
Battles/wars	American Revolutionary War French Revolutionary War Cornwallis's Retreat Napoleonic Wars Battle of Suriname
Awards	Knight Grand Cross of the Royal Guelphic Order
Relations	Murrough O'Brien, 1st Marquess of Thomond William O'Brien, 2nd Marquess of Thomond

Admiral James O'Brien, 3rd Marquess of Thomond, GCH (1769–1855), styled Lord James O'Brien from 1809 to 1846, was a British naval officer and Chief of Clan O'Brien.

O'Brien, born in 1769, was third son of Edward Dominic O'Brien, captain in the army (d. 1801). His mother was Mary Carrick, and his uncle, Murrough O'Brien, was first Marquess of Thomond. He inherited his title on the death of his brother William O'Brien, 2nd Marquess of Thomond