The Astartes Praeses were founded as a group of Space Marine Chapters tasked with guarding the borders of the Eye of Terror. It is a difficult and unforgiving task; the chapters are constantly beset by the Traitor Legions and even the occasional Black Crusade. Originally numbering twenty Chapters, eighteen now remain because one went traitor and the other was destroyed.
The full membership of the Praeses is unknown, but the following 13 Chapters have been confirmed as being part of the Praeses:
- Angels Eradicant
- Black Consuls and their counterpart, the White Consuls
- Brothers Penitent
- Crimson Scythes
- Iron Talons
- Knights Unyielding
- Marines Exemplar
- Night Watch
- Viper Legion
The Ultramarines Honour Company can be numbered amongst them, though it is not actually a Chapter, but it is tasked with the same purpose as the Astartes Praeses: to guard the Eye of Terror.
List of chapters that may or may not also be members of the Praeses:
- Sons of Malice - Participated in the 13th Black Crusade to reclaim their homeworld Scelus, a world in the Cadian sector. Which puts them existing exactly where you would want an Astartes chapter if you're trying to round up enough to guard the Eye of Terror. Shame about that whole being excommunicated thing.