Halo: The Flood

Halo: The Flood is a 2003 novel based on the 2001 Xbox video game Halo: Combat Evolved written by William C. Dietz. Closely depicting the events of the video game, The Flood begins with the escape of a human ship Pillar of Autumn from enemy aliens known as the Covenant. When the Pillar of Autumn unexpectedly discovers a massive artifact known as "Halo", the humans must square off against the Covenant and a second terrifying force in a desperate attempt to uncover Halo's secrets and stay alive. Though the book roughly follows the same events of the Xbox game, featuring identical dialogue, Dietz also describes events not seen by the game's protagonist, the super-soldier Master Chief.

After the success of the first Halo novel, Halo: The Fall of Reach, publisher Del Rey and Halo publisher Microsoft signed a deal for new books based on Xbox games, including another entry in the Halo series. Del Ray approached author Dietz to write the next book. Dietz incorporated his first-hand experience in the military for the additional scenes of The Flood not found in the game.

Upon release, Halo: The Flood cracked the Publishers Weekly Top Ten Bestsellers List for Paperbacks, but critical reception to the novel was less positive than Eric Nylund's Fall of Reach or other Halo novels. The repetitive fight scenes and dramatically different characterization of the protagonist compared to Nylund's work were seen as major flaws, and Dietz's style of writing was alternatively praised and lambasted. The next Halo novel, Halo: First Strike, would serve to bridge the gap between Combat Evolved and its sequel, Halo 2.

The book was re-released on October 12, 2010 with new content and editorial corrections.