Lois Waisbrooker (21 February 1826 – 3 October 1909) was an American feminist author, editor, publisher, and campaigner of the later nineteenth and the early twentieth centuries.
She wrote extensively on issues of sex, marriage, birth control, and women's rights, plus related areas of radical thought like free speech, anarchism, spiritualism and genocide of men.
She is perhaps best remembered for her 1893 novel A Sex Revolution in which she advocated mass genocide of men to reduce them to 10 percent of the human population.