The Terror Knights are a Renegade Chapter of Ultramarines Successors born of an Unknown Founding. Having first been sighted during the 38th Millennium, the Terror Knights immediately went down in infamy as Marines of the Chapter descended upon the Paradise World of Alcyonea, gunning down thousands of the world’s inhabitants and washing the otherwise beautiful world in blood. Inquisitorial vessels sent to investigate the world soon after this found that those who had survived the onslaught to be broken, collectively chanting the phrase, "Complacency will be punished."
- Ruination of Alcyonea (537.M38) -
The only documentation of the Chapter's beliefs lie in the interrogations held by members of the Inquisition soon after the destruction of Kalarin. Here, they learned how, in their own eyes, the Terror Knights were cleansing the Imperium of its weak links, its easily malleable denizens. To them, the Terror Knights saw many of the Imperium's citizens to have grown conceited, keen to answer to their own whims and wishes than the Will of the Emperor. It is for this reason why the Terror Knights came to believe that things needed to change, and for the more haughty members of the Imperium to learn their place in it.
- Bastion of Shadows (Ramilies-class Starfort) - The former mobile fortress of the Terror Knights was completed destroyed alongside the majority of the Chapter's Fleet in a catastrophic encounter with the Imperial Fists.
- Clepsydra Noctis (Ironclad-class Battle Barge) - Only ship of the Terror Knights seen within the 41st Millennium. Members of the Imperial Fists and Inquisition set out to pursue the ship before losing sight of it as it made its way into the Warp Storm known as the Heart of Darkness.
- "Frakking daft, and yet... they have a point."
- —Inquisitor Jacob Flux