James Sully (3 March 1842 - 1 November 1923) was an English psychologist.
He was born at Bridgwater, and was educated at the Independent College, Taunton, the Regent's Park College, University of Göttingen, where he studied under Lotze, and at Humboldt University, Berlin where he studied under DuBois-Reymond and Helmholtz. Originally destined for the Nonconformist ministry and in 1869 he became classical tutor at the Baptist College, Pontypool. In in 1871 he adopted a literary and philosophic career. He was Grote professor of the philosophy of mind and logic at University College, London, from 1892 to 1903, when he was succeeded by Carveth Read. An adherent of the associationist school of psychology, his views had great affinity with those of Alexander Bain. He wrote monographs on subjects such as pessimism, and psychology textbooks, some of the first in English, including The Human Mind (1892). His 1881 Ilusions was commended by Freud and Wundt.
Sully opened an experimental psychology laboratory at University College London in January 1889. In 1901 he was one of the founder members of the British Psychological Society and in fact called the meeting at which the Society was formed.