Warhammer 40K: Every Faction Ranked From Least To Most Evil

It was Horus, favoured of the Emperor’s primarchs, who first fell to the temptation of the Chaos Gods, corrupting a number of his fellow Primarchs and leading their Space Marine legions against the Emperor and mankind. The result was incalculable bloodshed and misery visited upon billions of the Empire’s citizens.

One could argue that the traitor legions were deceived by the Chaos Gods and as such their fall to a state of power-hungry monsters was not their fault. But if Horus’ final words to the Emperor, in which he repents and asks for forgiveness, are any indication, the Chaos Space Marines know that what they are doing is wrong and continue on regardless.

And what the worst of them can do is downright hideous. In the Daemonculaba they created arguably the worst fate in 40K, where captured woman are mutated alive into disgusting fleshy birthing chambers, within which are implanted living male adolescents, all in an attempt to create new Chaos Space Marines.

The only reason they are not at number is one because some of them, a very few, and no doubt privately, express regret for what they have done, and become.