John Michael Crichton (/ˈkraɪtən/; October 23, 1942 – November 4, 2008) was an American author, screenwriter and filmmaker. His books have sold over 200 million copies worldwide, and over a dozen have been adapted into films. His literary works heavily feature technology and are usually within the science fiction, techno-thriller, and medical fiction genres. Crichton's novels often explore human technological advancement and attempted dominance over nature, both with frequently catastrophic results; many of his works are cautionary tales, especially regarding themes of biotechnology. Several of his stories center on themes of genetic modification, hybridization, paleontology and/or zoology. Many feature medical or scientific underpinnings, reflective of his own medical training.

Crichton received an MD from Harvard Medical School in 1969 but did not practice medicine, choosing to focus on his writing instead. Initially writing under a pseudonym, he eventually published 25 novels in his lifetime, including: The Andromeda Strain (1969), The Terminal Man (1972), The Great Train Robbery (1975), Congo (1980), Sphere (1987), Jurassic Park (1990), Rising Sun (1992), Disclosure (1994), The Lost World (1995), Airframe (1996), Timeline (1999), Prey (2002), State of Fear (2004), and Next (2006). Four more novels, in various states of completion, were published after his death in 2008.

Crichton was also involved in the film and television industry. In 1973, he wrote and directed Westworld, the first film to use 2D computer-generated imagery. He also directed Coma (1978), The First Great Train Robbery (1978), Looker (1981), and Runaway (1984). He was the creator of the television series ER (1994–2009), and several of his novels were adapted into films, most notably the Jurassic Park franchise.

John Michael Crichton was born on October 23, 1942, in Chicago, Illinois, to John Henderson Crichton, a journalist, and Zula Miller Crichton, a homemaker. He was raised on Long Island, in Roslyn, New York, and he showed a keen interest in writing from a young age; at 16, he had an article about a trip he took to Sunset Crater published in The New York Times. Crichton later recalled, "Roslyn was another world. Looking back, it's remarkable what wasn't going on. There was no terror. No fear of children being abused. No fear of random murder. No drug use we knew about. I walked to school. I rode my bike for miles and miles, to the movie on Main Street and piano lessons and the like. Kids had freedom. It wasn't such a dangerous world... We studied our butts off, and we got a tremendously good education there."

Crichton had always planned on becoming a writer and began his studies at Harvard University in 1960 as an English major. During his freshman year, he conducted an experiment to expose a professor whom he believed was giving him abnormally low marks and criticizing his literary style. Informing another professor of his suspicions, Crichton submitted an essay by George Orwell under his own name. The paper was returned by his unwitting professor with a mark of "B−". He later said, "Now Orwell was a wonderful writer, and if a B-minus was all he could get, I thought I'd better drop English as my major." His differences with the English department and a desire to gain a more scientifically grounded education led Crichton to switch his major to biological anthropology. He graduated with a Bachelor of Arts summa cum laude in 1964, and was initiated into Phi Beta Kappa society.

Crichton received a Henry Russell Shaw Traveling Fellowship from 1964 to 1965, which allowed him to serve as a visiting lecturer in anthropology at the University of Cambridge in the United Kingdom. Crichton later enrolled at Harvard Medical School. Crichton later said "about two weeks into medical school I realized I hated it. This isn't unusual since everyone hates medical school – even happy, practicing physicians."

In 1965, while at Harvard Medical School, Crichton wrote a novel, Odds On. "I wrote for furniture and groceries", he said later. Odds On is a 215-page paperback novel which describes an attempted robbery at an isolated hotel on the Costa Brava in Spain. The robbery is planned scientifically with the help of a critical path analysis computer program, but unforeseen events get in the way. Crichton submitted it to Doubleday, where a reader liked it but felt it was not for the company. Doubleday passed it on to New American Library, which published it in 1966. Crichton used the pen name John Lange because he planned to become a doctor and did not want his patients to worry that he would use them for his plots. The name came from cultural anthropologist Andrew Lang. Crichton added an "e" to the surname and substituted his own real first name, John, for Andrew. The novel was successful enough to lead to a series of John Lange novels. Film rights were sold in 1969, but no movie resulted.

The second Lange novel, Scratch One (1967), relates the story of Roger Carr, a handsome, charming, privileged man who practices law, more as a means to support his playboy lifestyle than a career. Carr is sent to Nice, France, where he has notable political connections, but is mistaken for an assassin and finds his life in jeopardy. Crichton wrote the book while traveling through Europe on a travel fellowship. He visited the Cannes Film Festival and Monaco Grand Prix, and then decided, "any idiot should be able to write a potboiler set in Cannes and Monaco", and wrote it in eleven days. He later described the book as "no good". His third John Lange novel, Easy Go (1968), is the story of Harold Barnaby, a brilliant Egyptologist who discovers a concealed message while translating hieroglyphics informing him of an unnamed pharaoh whose tomb is yet to be discovered. Crichton said the book earned him $1,500 (equivalent to $13,563 in 2024). Crichton later said: "My feeling about the Lange books is that my competition is in-flight movies. One can read the books in an hour and a half, and be more satisfactorily amused than watching Doris Day. I write them fast and the reader reads them fast and I get things off my back."