Dudley Ernest Littlewood (7 September 1903, London – 6 October 1979, Llandudno) was a British mathematician known for his work in group representation theory.
He read mathematics at Trinity College, Cambridge where his tutor was J.E. Littlewood (they were not related). He was a lecturer at University College, Swansea from 1928 to 1947, and in 1948 took up the chair of mathematics at University College of North Wales, Bangor, retiring in 1970.
He worked on invariant theory and group representation theory, especially of the symmetric group, often in collaboration with Archibald Read Richardson of Swansea. They introduced the immanant of a matrix, studied Schur functions and developed the Littlewood–Richardson rule for their multiplication. Littlewood was also interested in the application of representation theory to quantum mechanics.