Henry Havelock Ellis, known as Havelock Ellis (2 February 1859 – 8 July 1939), was an English physician, writer, progressive intellectual and social reformer who studied human sexuality. He was co-author of the first medical textbook in English on homosexuality in 1897, and also published works on a variety of sexual practices and inclinations, as well as transgender psychology. He is credited with introducing the notions of narcissism and autoeroticism, later adopted by psychoanalysis