The novels often took liberties with the plot of the games by exploring events

The novels often took liberties with the plot of the games by exploring events occurring outside and beyond the games. This often meant that the novels would later be contradicted by the games and, on a few occasions, themselves.[45] One notable addition from the novels is the original character Trent, who often served as a mysterious behind-the-scenes string-puller Cosplay Costumes who aided the main characters. Perry's novels were translated and released in Japan with new cover arts by Wolfina.[46] Perry's novels, particularly The Umbrella Conspiracy, also alluded to events in Biohazard: The Beginning, such as the disappearance of Billy Rabbitson and Brian Irons' bid to run for Mayor. A reprinting of Perry's novels with new cover artwork began in 2012 to coincide with the release of Resident Evil: Retribution and its respective novelization.

There was also a trilogy of original Biohazard novels in Japan. Hokkai no Yōjū (北海の妖獣?, lit. "The Strange Beast of the North Sea") was published in 1998 and was written by Kyū Asakura and the staff of Flagship. Two additional novels were published in 2002, To the Liberty by Suien Kimura and Rose Blank by Tadashi Aizawa. While no official English translation of these novels has been published yet, the last two books were translated into German and published in 2006.

Novelizations of four of the five films; Genesis, Apocalypse, Extinction and Retribution, were written by Keith R. A. DeCandido, while Retribution was written by John Shirley, though Afterlife did not receive a novelization. The Genesis novel was published over two years after that film's release while the Extinction novel was released in late July 2007, two months before the film's release. There was also a Japanese novelization of the first film, Resident Evil Costumes unrelated to DeCandido's version, written by Osamu Makino. Makino also wrote two novels based on the game Resident Evil: The Umbrella Chronicles. The books are a two-part direct novelization of the game and have been published in Japanese and German only. The first novel which was titled Biohazard: The Umbrella Chronicles Side A in Japan and Resident Evil: The Umbrella Chronicles 1 in Germany was released on December 22, 2007. The second novel which was titled Biohazard: The Umbrella Chronicles Side B in Japan and Resident Evil: The Umbrella Chronicles 2 in Germany was published in January 2008