Denis Murphy was born in Nambour, Queensland, on 6 August 1936. He studied at the University of Queensland, attaining a Bachelor of Arts (1964), Diploma of Physical Education (1959), and PhD (1972). In 1966 he was appointed as a tutor in the University of Queensland History Department; in 1979 he was promoted to Reader (now Associate Professor). His interests were centred on Australian history, particularly Queensland politics. His best-known work was a biography of the Queensland Labor Premier, T J Ryan: A Political Biography (1975). This was awarded the Australian Literary Foundation Award in 1976. Murphy was a member of the Australian Labor Party, and from 1980 to 1984 was President of the Queensland Branch. He was a leading figure in the reform of the Queensland Branch of the Australian Labor Party. From 1983 to 1984 he was state Member of the Legislative Assembly for Stafford. He died on 21 June 1984.