Adnan Oktar (1956–), who usually goes by the pen name Harun Yahya, is a Turkish author and publisher of a number of books advocating old earth creationism from an Islamic perspective. He is best known for writing and publishing The Atlas of Creation (under the Harun Yahya pseudonym), and for then distributing it to schools, universities and academics across Europe and the United States without any prior solicitation. He has also published a book titled The Evolution Deceit which was distributed within Turkey. Oktar has written more than 300 books, mostly on evolution - but also on the Qur'an, Freemasonry, Judaism and Zionism. A number of these works are intended for children.
He has also written an anti-Semitic book titled The Holocaust Lie. He has subsequently changed his opinions and now claims to not be anti-Semitic, and instead blames "Darwinism" for the origin of anti-Semitism.
Oktar's legal actions have resulted in a variety of websites being blocked in Turkey, including Google Groups, richarddawkins.net (following the publication of a Turkish translation of an article by Dawkins criticising Oktar/Yahya), the Union of Education and Scientific Workers and Vatan, a Turkish newspaper website.