Madalyn Murray O'Hair, American activist, founded American Atheists (d. 1995)
Madalyn Murray O'Hair (née Mays; April 13, 1919 – September 29, 1995) was an American activist, supporting atheism and separation of church and state. In 1963 she founded American Atheists and served as its president until 1986, after which her son Jon Garth Murray succeeded her. She created the first issues of American Atheist Magazine.

O'Hair is best known for the Murray v. Curlett lawsuit, which challenged the policy of mandatory prayers and Bible reading in Baltimore public schools, in which she named her first son William J. Murray as plaintiff. Consolidated with Abington School District v. Schempp (1963), it was heard by the United States Supreme Court, which ruled that officially sanctioned mandatory Bible-reading in American public schools was unconstitutional. The Supreme Court had prohibited officially sponsored prayer in schools in Engel v. Vitale (1962) on similar grounds. After she founded the American Atheists and won Murray v. Curlett, she achieved attention to the extent that in 1964 Life magazine referred to her as "the most hated woman in America". Through American Atheists, O'Hair filed numerous other suits on issues of separation of church and state.

In 1995, O'Hair, her second son Jon Garth Murray (known as "Garth"), and her granddaughter and adopted daughter Robin Murray O'Hair (daughter of O'Hair's first son, William J. Murray, and Murray's high school girlfriend, Susan), disappeared from Austin, Texas. Garth Murray had withdrawn hundreds of thousands of dollars from American Atheists' funds, and there was speculation that the trio had absconded. David Roland Waters, a convicted felon and former employee of American Atheists, was eventually convicted of murdering the O'Hairs. The bodies were not found until Waters led authorities to their burial place following his conviction.