McDonald, Denis Ronald (1910–83), diplomat, was born 22 February 1910 at Clondalkin, Co. Dublin, son of John McDonald, ticket collector, and Ellen McDonald (née Gamble). He was educated at UCC (BA (hons) (1930), H.Dip.Ed. (1931)). After teaching Irish and mathematics at Waterpark College, Waterford, he entered the civil service in 1934 as assistant inspector of taxes in the revenue commissioners. A gifted linguist, McDonald had, apart from Irish and English, a thorough knowledge of French, German, Italian, and Spanish, with a working knowledge of Swedish. He took first place in the 1937 cadetship examinations and joined the Department of External Affairs in 1938. He was appointed secretary of the Irish legation in Rome (June 1941), followed by an appointment as secretary of the Irish legation to France (1943), and returned to headquarters in Dublin as first secretary in 1946. In 1947 he was appointed counsellor to the Irish embassy to the Holy See. McDonald served as chef de protocol at headquarters from 1949 to 1952, when he was appointed counsellor in the political division, then in its heyday at the nerve centre of external affairs, working closely with the minister for external affairs and the secretary of the department on the political problems of the day.
In 1954 he was again posted overseas, as minister plenipotentiary to Belgium; he was appointed ambassador to Belgium in 1959 and, concurrently, Ireland's head of mission to the EEC. In 1960 he returned to Paris as Irish ambassador, serving concurrently as Irish permanent delegate to the OECD and UNESCO. He was appointed ambassador to Italy and (concurrently) Turkey in 1966. In 1972, as ambassador to Italy, McDonald deposited Ireland's instrument of ratification of the treaty of accession to the EEC. He was Irish ambassador to Egypt (1975–6), and retired in 1977. A Knight Commander of the Order of Saint Gregory the Great, Denis McDonald died 25 August 1983 in St Vincent's Private Nursing Home, Dublin, and was buried in Deansgrange cemetery on 27 August.
He married (1941) Una Sheehan; they had two children, Cliona and Brian.