Havelock Ellis was a British physician, writer, and social reformer best known for his pioneering work in the field of sexology. He wrote over a dozen books on the subject, including Studies in the Psychology of Sex, which was published in seven volumes between 1897 and 1928. He also wrote several novels, including The New Adam (1912) and The Chastening (1913). He was an advocate for women's rights and was a founding member of the British Society for the Study of Sex Psychology.