Sir Eric Robert Dalrymple Maclagan KCVO CBE FSA (4 December 1879 – 14 September 1951) was a British museum director and art historian.
Born on 4 December 1879 in London, Maclagan was the only son of William Dalrymple Maclagan, Archbishop of York and his second wife Augusta Anne, daughter of the sixth Lord Barrington. He had a sister and two half-brothers. Educated at Winchester College, he read classics at Christ Church, Oxford, graduating in 1902.
In 1905 Maclagan joined the staff at the Victoria and Albert Museum as an assistant in the Textiles Department. During his time there he produced a Guide to English Ecclesiastical Embroideries. After a time he transferred to the Department of Architecture and Sculpture where he worked under Mr A B Skinner. He became head of this department when Skinner died in 1908. One of his first tasks was to rearrange the collection of Italian sculpture and start the large Catalogue of Italian Plaquettes, which was published many years later in 1924.
In 1916 Maclagan was temporarily transferred to the Foreign Office, and later to the Ministry of Information. He became head of the Ministry's bureau in Paris and its controller for France in 1918. In 1919 he was attached to the British peace delegation and was present at the signing of the Treaty of Versailles. For his services in France, Maclagan was made a CBE in 1919. While in Paris, he was a member of the "set" surrounding the novelist Edith Wharton.