Murrough O'Brien, 1st Marquess of Thomond

Murrough O'Brien, 1st Marquess of Thomond KP, PC (1726–1808), 5th Earl of Inchiquin (1777–1800), wearing purple coat, white waistcoat, pale blue sash and breast star of the Order of Saint Patrick (Henry Bone)

Sir Murrough O'Brien, 5th Baron O'Brien of Burren, 1st Baron Thomond of Taplow, 10th Baron & 5th Earl of Inchiquin, 1st Marquess of Thomond KP, PC (Ire) (1726 – 10 February 1808), known from 1777 to 1800 as the 5th Earl of Inchiquin, was an Irish peer, soldier, politician, and Chief of Clan O'Brien.