Douglas Mesner, better known as Lucien Greaves,[6] is an American social activist and co-founder of, and spokesperson for, The Satanic Temple.

[13] Greaves has spoken on the topics of Satanism, secularism, and The Satanic Temple at universities throughout the United States,[14][15][16] and he has been a featured speaker at national conferences hosted by American Atheists,[17] the American Humanist Association,[18] and the Secular Student Alliance.

[19] Greaves has been instrumental in setting up the Protect Children Project, the After School Satan project, and several political demonstrations and legal actions designed to highlight social issues involving religious liberty and the separation of church and state.

[5][22] Greaves and his colleagues envisioned The Satanic Temple as a "poison pill" in the Church/State debate: Satanists asserting their rights and privileges where religious agendas have imposed themselves upon public affairs, serving as a reminder that such privileges are for everybody, and can provide a religious agenda beyond the current narrow understanding.

[13] Greaves contributed the foreword to The Little Book of Satanism by La Carmina (2022)[23][24] as well as artwork for multiple endeavors by Shiva Honey.