A codex (often pluralized as codexes, though the correct pluralization is codices), in the Warhammer 40,000 tabletop wargame, is a rules supplement containing information concerning a particular army, environment, or worldwide campaign.
Codices for particular armies were introduced for the second edition of the game. The third edition rendered these obsolete, and a new series began, including introducing codices for battlezones and campaigns.
Unless superseded by newer versions, the 3rd edition codices remain valid for the 4th and 5th editions of Warhammer 40,000. Games Workshop no longer produce campaign or battlezone codices, instead releasing 'expansions'. 'Codex' is now a term solely used for army books.
A codex normally contains:
- Army list - A list of the units, characters and vehicles that can be chosen for use in a battle. This includes their characteristic values, information on their weapon options, and any limitations on their use. Each item also has a points value, with more powerful units costing more points, so that battles are fought between balanced armies.
- Background - Information about the force and its place in the Warhammer 40,000 universe. This includes artwork, short stories, and copies of fictional documents from the future.
- Hobby section - Information on collecting, building and painting an army from the codex. This features outstanding example models painted by veteran hobbyists and Games Workshop's 'Eavy Metal team.
- Special characters - Older Codices have this as a separate section. Newer ones include them with the army list. Contains background information and rules for fielding remarkable individuals from the army. Examples include Marneus Calgar in Codex: Space Marines and Ghazghkull Mag Uruk Thraka in Codex: Orks.