Luis Martín-Santos (born Nov. 11, 1924, Larache, Morocco—died Jan. 21, 1964, San Sebastian, Spain) was a Spanish psychiatrist and novelist.

Martín-Santos received a medical degree from the University of Salamanca and, in 1947, a doctorate in psychiatry from the University of Madrid. From 1951 until his death, he was director of the Psychiatric Sanitorium in San Sebastián. He tried to develop a psychology of the whole person, and he published his ideas in Dilthey, Jaspers y la comprensión del enfermo mental (1955; “Dilthey, Jaspers, and the Understanding of Mental Illness”). In 1962 he published his novel Tiempo de silencio (“Time of Silence”), the first of a projected trilogy. The novel is about a medical student, Pedro, thrust among inhabitants of the Madrid slums and confronted with their often violent adaptation to severe conditions. Events force him to confess to a crime of which he is innocent and to face in silence the consequences—even after his innocence has been proved. The novel has been compared in structure and style to James Joyce’s Ulysses. The sequel, Tiempo de destrucción (1975; “Time of Destruction”), was unfinished when Martín-Santos was killed in an automobile accident in 1964. His psychological work, Libertad, temporalidad y transferencia en la psicoanálisis existencial (“Freedom, Temporality, and Transference in Existential Psychoanalysis”), was published posthumously that year.