Neil Quintus Dias commonly known as N.Q. Dias, was a Sri Lankan civil servant. A career officer of the Ceylon Civil Service, he was the Permanent Secretary of Defence and Foreign Affairs from 1960 to 1965, serving as the de facto Chief Adviser to Prime Minister Sirimavo Bandaranaike and as Ceylon's High Commissioner to India from 1970 to 1972. A Sinhalese Buddhist nationalist, N.Q. Dias was known for planning and executing many of the Sinhalese Buddhist nationalist policies of the Bandaranaike's Freedom Party.