Margaret Downey (born August 16, 1950) is a nontheist activist who is a former President of Atheist Alliance International and founder and president of the Freethought Society (formerly Freethought Society of Greater Philadelphia).

[1][2] She also founded the Anti-Discrimination Support Network, which reports and helps deal with discrimination against atheists.

[1] When her father left, she adopted a family friend "Uncle Floyd" as a father-figure who encouraged Downey into atheism.

[1] Downey has been active in a variety of causes including feminism and anti-smoking campaigns before becoming a public representative of atheism.

[9] Downey is also affiliated with a variety of other organizations that promote atheism and the separation of church and state such as Freedom From Religion Foundation of which she is a board member and the American Humanist Association of which she is a past board member.