Dan Barker (born June 25, 1949) is a prominent American atheist activist who served as a Christian preacher and musician for 19 years but left Christianity in 1984.

Barker received a degree in Religion from Azusa Pacific University and was ordained to the ministry by the Standard Community Church, California, in 1978. He served as associate pastor at a Religious Society of Friends (Quaker) church, an Assembly of God, and an independent Charismatic church. To this day, he receives royalties from his popular children's Christian musicals, "Mary Had a Little Lamb" (1977), and "His Fleece Was White as Snow" (1978), both published by Manna Music and performed in many countries. In 1984 he announced to his friends that he was an atheist.

A successful musician, Barker has composed over 200 songs that have been published or recorded. He is the current co-president with his wife Annie Laurie Gaylor of the Freedom From Religion Foundation, an American Freethought organization that promotes the separation of church and state. Barker is co-host of Freethought Radio, a Madison, Wisconsin based radio program for atheists, agnostics, and other freethinkers that has included interviews with Richard Dawkins, Sam Harris, Steven Pinker, Julia Sweeney, and Michael Newdow. His foundation published his book Losing Faith in Faith: From Preacher to Atheist, and he has written numerous articles for Freethought Today, an American freethought newspaper.

Annie Laurie Gaylor (born in Tomah, Wisconsin on 2 November 1955) is co-founder of the Freedom From Religion Foundation and, with her husband Dan Barker, is the current co-president. She is also editor of the organization's newspaper, Freethought Today, which is published ten times per year. She is a self-described feminist and liberal. She is the author of several books, including Woe to the Women: The Bible Tells Me So, Betrayal of Trust: Clergy Abuse of Children, and Women Without Superstition: "No Gods — No Masters." She is a 1980 graduate of the University of Wisconsin–Madison School of Journalism.

Gaylor and her mother, Anne Nicol Gaylor, and the late John Sontarck, founded the Freedom From Religion Foundation in a meeting around the Gaylors' dining room table in 1978. She met Barker at The Oprah Winfrey Show in 1984. They began dating six months later and married in 1987. They have a daughter, Sabrina Delata.

Gaylor co-hosts a one hour weekly radio show with Barker. Freethought Radio was launched on October 6, 2007, on Air America.