Which Chapters are fighting in the Dark Imperium?

[Son of Sacrifice]

We know that the Great Rift is very difficult if not almost impossible to cross, so which chapters are stuck on the dark side of the Imperium? Is there a definitive list anywhere?

[Sword Brother Adelard]

Not sure about definitive. But you have the Spears of the Emperor, the Celestial Lions and some Black Templars duking it out in Allara's Veil. (Not sure about that spelling, I have only listened to the Audio Book)

 

Also, it appears that most of the Blood Angel Successors are on the dark side.

[Qkhitai]

Chapters with their homeworlds (most likely) in Imperium Nihilus, or who were likely to have been stationed there in bulk, would be:

 

Angels of Vigilance?

Aurora Chapter

Blood Angels

Blood Drinkers

Blood Swords

Celestial Lions

Crimson Paladins

Dark Sons

Death Spectres

Doom Legion

Excoriators

Exorcists

Hawk Lords

Honoured Sons

Iron Hands

Iron Knights

Iron Snakes

Knights of the Raven?

Legion of Night

Marines Errant

Night Watch

Novamarines

Rainbow Warriors

Silver Skulls

Sons of Orar?

Star Dragons

Storm Hawks

Storm Wardens

Twilight Swords

 

Not an exact science, and some might be inaccurate, but that's what I've come up with after a quick trawl of the wiki. Although just because their homeworld was there, it doesn't necessarily mean that the entire chapter would be there too. As good a yardstick as any though.

Edited December 22, 2019 by Qkhitai

[Son of Sacrifice]

That's a great list, thanks for doing the work.

[Claws and Effect]

I can verify the Knights of the Raven's homeworld of Coralax is indeed in Imperium Nihilus.

 

How much of the Chapter is on that side of the rift though, I do not know.

[Ishagu]

Spears of the Emperor are also in the Dark Imperium.

[Lucerne]

Blood Ravens were explicitly on the wrong side of the Rift per their Index.