David Richard Morier (1784–1877) was an English diplomat.
The third son of Isaac Morier, consul-general to the Turkey Company at Constantinople, he was born in Smyrna on 8 January 1784, was educated at Harrow School, and entered the diplomatic service. In January 1804, at age 20, he was appointed secretary to the political mission sent by the British government to Ali Pasha and the Turkish governors of the Morea and other provinces, with a view to counteracting the influence of France in south-east Europe. In May 1807 he was ordered to take entire charge of the mission, but the continuing rupture of diplomatic relations between England and the Ottoman Empire defeated his negotiations.
Morier was shortly transferred to Sir Arthur Paget's mission, at the Dardanelles. He was despatched on special service to Egypt, where he was instructed to negotiate for the release of the British prisoners captured by Muhammed Ali during the Alexandria expedition of 1807. In the summer of 1808 he was attached to Robert Adair's embassy, and with Stratford Canning, assisted in negotiations which resulted in the Treaty of the Dardanelles of 5 January 1809. Back in Constantinople, with the exception of a mission to Tabriz from October 1809 to the following summer, he remained at the embassy, first under Adair, and then (1810–12) as secretary of legation under his successor, Stratford Canning.
At the end of Canning's appointment, Morier accompanied him (July 1812) on his return to England. In 1813 he was attached to Lord Aberdeen's mission to Vienna, and during the years 1813-1815 was employed in the negotiations around the fall of Napoleon. He was with Lord Castlereagh at the conferences at Chatillon-sur-Seine, and assisted in the preparation of the Treaty of Paris (1814). In the same year he attended the foreign minister at the Congress of Vienna, and, when the Duke of Wellington succeeded Castlereagh, Morier remained as one of the secretaries. In July 1815, after the final overthrow of Napoleon, Morier accompanied Castlereagh to Paris, and was occupied till September in drafting the Treaty of Paris (1815).