One of the few facts about Hubbard's life that critics and Scientologists agree with is his career as a fiction writer. During the 1930s he was a prolific author of pulp fiction stories, producing a large number of short stories and novellas in various genres (though he wrote primarily for science fiction and fantasy). Critics generally cite the novels Fear and Final Blackout as Hubbard's best works of this period, though a number of his other early works of fiction are also heavily promoted by Scientology, including Ole Doc Methuselah, Typewriter in the Sky and Slaves of Sleep / Masters of Sleep. (Fans of light-hearted pulp fiction adventures will enjoy these latter books, though readers shouldn't expect anything more than fast-paced escapist adventure stories here.)
Hubbard put his career as a writer on hold to enter military service in World War II (details of which are explored on the Web site "Ron the War Hero"). Following his return to the United States, he associated for a time with Jack Parsons (a follower and disciple of Aleister Crowley). Shortly after this, Hubbard turned to the field of self-help and psychoanalysis, publishing in 1950 the book he would be most known for: Dianetics: The Modern Science of Mental Health. Scientology promotes this book as the greatest breakthrough in the history of mankind; and while this claims is viewed with suspicion by observers, it is true that Dianetics was indeed a best-seller. It spawned a short-lived fad that died out almost as fast as it appeared, though Hubbard tried to extend the life of Dianetics as much as possible. He followed Dianetics with Science of Survival and finally Dianetics 55. But as the Dianetics craze faded out in the early 1950s, he decided to turn to religion instead.
In 1953 Hubbard published Scientology: The Fundamentals of Thought, and he devoted himself exclusively to the promotion of his newly created religious movement. All of his books published between 1953 and 1980 were written especially for Scientology, and newcomers to Hubbard's works may be confused by the elaborate jargon and redefinition of words he incorporated into his writing from the 1950s onward. Hubbard gave numerous lectures and wrote essays for Scientology during the 1950s and 1960s, and collections of these essays were published as books to supplement Scientology's educational "courses." Publicly available collections of Hubbard's Scientology writings include Scientology: A New Slant On Life and Self Analysis.
(Because the majority of Hubbard's books of the 1950s through 1970s were written exclusively for Scientology, the organization founded its own publishing company to allow him to write and publish literally anything he wished, without having to comply to the standard editorial process that most published authors adhere to. This company, Bridge Publications, continues to publish and promote Hubbard's works today.)
Hubbard's Scientology teachings brought him into conflict with the IRS, the Food and Drug Administration, and the FBI, as well as the "psychiatric establishment," as Scientology claims (details of his legal battles are provided in the book A Piece of Blue Sky: Scientology, Dianetics and L. Ron Hubbard Exposed). His writings of the later 1960s and 1970s were more private and secluded, and have rarely been made available to the public. (The secret documents of Scientology, the "Operating Thetan Levels," were written during this time.) However, in the years before his death, he made an effort to return to his roots and re-establish himself in the field of science fiction. 1980 saw the publication of Battlefield Earth: A Saga of the Year 3000, a huge novel that returned to Hubbard's days of writing action-packed adventure stories. Despite its being criticized by some as "juvenile pulp fiction," Battlefield Earth has been embraced by science fiction fans as a fast-paced, action-packed escapist novel that does not emphasize its ties to Scientology.
"Battlefield Earth" would have been a satisfactory capstone to Hubbard's literary career. But in the final years of his life, he then published the "Mission Earth" series: a ten-book adventure story that was seen as a much more blatant attempt to introduce Scientology teachings into popular culture (the first volume of the series is Invaders Plan, The: Mission Earth Volume 1). The "Mission Earth" books are frequently cited by science fiction fans as among the worst science fiction series of all time. More forgiving fans usually cite "Battlefield Earth" as Hubbard's best book of the modern era.