Operation Clambake, also referred to by its Web address, Xenu.net, is a website and Norway-based non-profit organization launched in 1996 that publishes mostly critical information about the Church of Scientology. It is owned and maintained by Andreas Heldal-Lund, who has stated that he supports the rights of all people to practice Scientology or any religion, though Operation Clambake has also referred to the Church of Scientology as: "a vicious and dangerous cult that masquerades as a religion." The Web site includes texts of petitions, news articles, exposés, and primary source documents. The site has been ranked as high as the second spot in Google searches for the term "Scientology".

The term for the organization refers both to a traditional clam bake, as well as the notion from L. Ron Hubbard's Scientology: A History of Man that humans follow a "genetic line" which includes clams, and that our psychological problems are impacted by past experiences. The domain name Xenu.net is a reference to the character Xenu from secretive "OT III" Scientology documents.

In 1996, the site was one of the first locations on the internet to host secret Scientology documents pertaining to Xenu and OT III. Shortly thereafter, the Church of Scientology attempted to get this material removed from Operation Clambake and other internet sites, through letters written by counsel, and the Digital Millennium Copyright Act. After receiving a DMCA takedown notice, Google removed many Xenu.net pages from its indexes, which decreased the site's pageranking in searches for "Scientology." This inspired Google to contribute to the Chilling Effects archive, informing others about material missing from Google indexes due to DMCA takedown notices and other legal threats.

Operation Clambake has been consulted by news media organizations and other groups for information on Scientology and related organizations. Dateline NBC cited the organization in a 1998 investigative journalism piece, as have other publications including The Wall Street Journal, The New York Times and the Associated Press. Xenu.net has been included as required reading in a New York University course on "Copyright and Censorship," and in 2003 webmaster Andreas Heldal-Lund received the 2003 Leipzig Human Rights Award by the European-American Citizens Committee for Human Rights and Religious Freedom in the USA, an organization opposed to the Church of Scientology.