Sir Robert Adair GCB (24 May 1763 – 3 October 1855) was a distinguished British diplomat, and frequently employed on the most important diplomatic missions.
He was the son of Robert Adair, sergeant-surgeon to George III, and Lady Caroline Keppel, daughter of Willem Anne van Keppel, 2nd Earl of Albemarle.
He was educated at Westminster School and the University of Göttingen, and then studied law at Lincolns Inn, but hardly practised as a barrister.
He hoped to gain office as Under-secretary of State to Charles James Fox, but he was in opposition.
In June 1808, George Canning transferred him to Constantinople.
He was created a KCB in that year for his services there.
He was appointed a Privy Counsellor in 1828.
He was employed in Belgium from 1831 to 1835, where he succeeded in preventing a war between Belgium and The Netherlands.
This exploit won for him the rank of GCB and a pension of £2000 per year from 1831, and also the grand'cross of the Belgian order of Leopold in 1835.
He then visited Prussia.
In the 1840s, he published memoirs of his diplomatic activities in the 1800s.