A codex in Warhammer 40,000 is a supplement containing information on a particular army.

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, 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 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 - Contains background information and rules for fielding remarkable individuals from the army. Examples include Marneus Calgar in Codex:Space Marines and Ghazghkull Thraka in Codex:Orks

List of Codexes as of March 2005:

Army Codexes

• Space Marines(4th Edition)
  • Blood Angels
  • Dark Angels
  • Space Wolves
  • Black Templars(4th Edition, coming soon)
• Orks
• Tyranids
• Chaos Space Marines
• Imperial Guard
  • Catachans
• Eldar
  • Craftworld Eldar
• Dark Eldar
• Necrons
• Tau
• Daemonhunters
• Witchhunters

Battlefield Codexes

• Cityfight

Event Codexes

• Armageddon
• Eye of Terror