Havelock Ellis (1859 - 1939)

Henry Havelock Ellis, known as Havelock Ellis (2 February 1859 – 8 July 1939), was a British physician, writer, 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, including transgender psychology.