Codex: Space Marines (4th Edition)

Codex: Space Marines is an expansion book for the Games Workshop tabletop game Warhammer 40,000. This edition of the book was published for the first time in 2005, and is for the 4th edition of Warhammer 40,000. It was the first Codex released for that edition of the game.

This was only the 2nd generic Space Marine codex, although it focused much more strongly on the Ultramarines Chapter than its predecessor. It covered the largest number of units for the Space Marines thus far, as it attempted to collate a number of units that had become more spread out as numbers of Space Marine sub-codices had been released. It also attempted to tap into the Space Marines' imagery as 'warrior monks'. Overall the book made the Space Marines feel more ancient and elite than previous incarnations had.

The book has 80 pages and the cover is printed in colour while the majority of the book remains in black and white, although there are several pages of colour images of miniatures at the back of the book. The cover features Marneus Calgar and his Honour Guard fighting a large Tyranid force, supported by Terminators and other Ultramarines formations. The back cover image is of a unit of five Ultramarines Veterans surrounded by Ork Boyz and what could be at least one Ork Dreadnought.