Bare-faced Messiah: The True Story of L. Ron Hubbard is a posthumous biography of Scientology founder L. Ron Hubbard by British journalist Russell Miller. First published in the United Kingdom on 26 October 1987, the book takes a critical perspective, challenging the Church of Scientology's account of Hubbard's life and work. It quotes extensively from official documents acquired using the Freedom of Information Act and from Hubbard's personal papers, which were obtained via a defector from Scientology. It was also published in Australia, Canada and the United States.

The Church of Scientology strongly opposed the book's publication. The organization was accused of organising a smear and harassment campaign against Miller and his publisher, though it strenuously denied this accusation, and a private investigator involved in the campaign denied that the organization was his client. However, a leak of internal Scientology documents to the press in 1990 disclosed many details of the campaign. The organization and related corporate entities attempted to prevent the book's publication in court, resulting in cases that reached the Supreme Court of the United States, the Court of Appeal of England and Wales and the Federal Court of Canada. The U.S. Supreme Court's decision to let a lower court's ruling stand, denying fair use protection for the book's use of unpublished sources, set a precedent favouring copyright protection of unpublished material over biographers' freedom of speech. Courts in the UK and Canada took an opposite view, allowing publication of Bare-faced Messiah in the public interest.

Reviews of the book have been broadly positive — one calling it "the best and most comprehensive biography of L. Ron Hubbard" — and praise the quality and depth of Miller's research. The Scientology organization has been less complimentary; the executor of Hubbard's estate called it "a scumbag book  ... full of bullshit" in a court deposition in the U.S.