Novelization First

This is when a Novelization of a work (usually a film) arrives on store shelves before the work's own debut, resulting in Spoilers to those who read it. It can happen in any media, and is increasingly common in big-budget titles.

This, obviously, does not apply to cases where the original work is a book series itself (e.g. Harry Potter) and receives a re-release right before its film adaptation hits the box office. (Unless the novelization is specifically based on the adaptation, instead of the original source.)

Subtrope of Adaptation First. See also: Sequel First.

Film

 * Famously, Star Wars: every single movie plus adaptations of many Star Wars the Clone Wars episodes and games like The Force Unleashed. Notably, the novelization of the original Star Wars was released six months before the movie, in December 1976, though this can be excused as part of the promotion of a movie whose success was not at all assured.
 * All prequel movies had novelizations, comic adaptations and Illustrated screenplays released a month before the movie's release. Add in the official soundtrack and the video game adaptation and by the time you see the movie for the first time, you could not only know what happens, but every single line as well.
 * Isaac Asimov's novelization of Fantastic Voyage came out six months before the movie, leading many people to believe that Asimov originated the story, which he had to constantly deny. Some confused fans even complained about the movie getting things wrong because the novelization had corrected a few glaring plot holes that were still present in the film.
 * Eventually he had to write an entire science article both to sort this out and explain in how many ways the scientific problems of shrinking were ignored by the screenwriters.
 * The novel for Spider-Man 3 was in bookstores, and even Wal-Mart, months before the actual movie was released.
 * Iron Man 2: Same as above.
 * The novel The Ice People was written as an adaptation of a big-budget movie that never got off the ground.
 * People studying literature and old German cinema to this day debate whether Metropolis was a movie adaptation of a book or the movie script got made into a novel. The novel came out first, though.
 * Alpha and Omega.
 * The novelization of The Funhouse, by Owen West (a pseudonym of Dean Koontz), came out the year before the film.
 * The novelization of Red Riding Hood was released three months before its theatrical debut
 * Partially averted. The ending is not included in the novelization; it is online, but will not be available until the movie comes out.
 * The novelizations for all three Transformers films were released before the film's release. They also each had a prequel novel released two months prior of the release of the novelizatios

Live Action TV

 * Novelizations of the Alien Nation Made-for-TV Movies Dark Horizon (1994) and Body and Soul (1995) were both published in 1993, based on unfilmed scripts for future episodes of the series.
 * This supposedly happened in the UK with the Doctor Who 20th anniversary special The Five Doctors.

Video Games

 * The Starcraft: Ghost book came out around 2006. The computer game is indefinitely postponed.

Western Animation

 * The novelization of Sozin's Comet, the Grand Finale of Avatar: The Last Airbender, came out months before the actual episodes were shown on Nickelodeon.
 * The novelization of Phineas and Ferb Across the Second Dimension was available on June 28, 2011, earlier than the movie itself aired on Disney Channel.
 * Pretty much any given Disney film from the 90s and onward has novelizations and other merch coming out before the films
 * Partially averted, in that many of the novelizations will prematurely end, and visual guides will be missing siginificant events and props from the end.