Certainly one of the longest running and most beloved science fiction sagas is WarHammer 40K. This story, which was born as a futuristic version of the TTG WAr Hammer, did not take long to become one of the cult sagas within the SciFi genre. The first book of this fantastic story was published in 1997 and currently there are more than 60 books published with various sagas and stories which makes it very difficult to know how or where to start reading this story. Here is one of the existing suggestions, courtesy of Grim Dark Magazine.

Gaunts Ghost by Dan Abnett

Ultramarines by Graham McNeill

Space Wolves by William King

Eisenhorn by Dan Abnett

The Beast Arises by Various

Night Lords by Aaron Dembski-Bowden

The Horus Heresy by Various