Mary Coffin Ware Dennett (April 4, 1872 – July 25, 1947) was an American women's rights activist, pacifist, homeopathic advocate, and pioneer in the areas of birth control, sex education, and women's suffrage.
She co-founded the Voluntary Parenthood League, served in the National American Women's Suffrage Association, co-founded the Twilight Sleep Association, and wrote a famous pamphlet on sex education and birth control.