David Allardice Webb or D. A. Webb (12 August 1912 – 26 September 1994) was an Irish botanist and chair of botany at Trinity College, Dublin from 1949 to 1966. He was son of George and Dr Ella Webb. In Ireland he had studied under Henry Horatio Dixon and also studied in the United Kingdom. In addition to botany he edited a history of Trinity College with R. B. McDowell and published a book on the history of art in Trinity College. In 1982 he received the Boyle Medal of the Royal Dublin Society. His botanical specialties included his work as a leading taxonomist of Saxifraga. He died in a car accident on his way to the University of Reading's herbarium. The 8th edition of An Irish Flora was renamed Webb's An Irish Flora in his honour.