The Space Marines Codex is an expansion book for the Games Workshop Table Top game Warhammer 40,000. This book was published for the first time in 1998, and is for the 3rd edition of Warhammer 40,000.

The book has 48 pages and the cover is printed in color while the majority of the book remains in black and white, although there are sixteen pages, in addition to the front and back inside cover, of colour images of miniatures.