For at least the last 200 millennia, the Dark Eight have led the armies of the Baatezu, guiding Law's side of the Blood War. These preeminent examples of their kind, by merely surviving over the eons, have proven their skills in both strategy and politics, though they do their best to keep the latter from impacting the ways of the Baator Legions.
Once nine, the origins of the Dark Eight and their position in the heirarchy of the baatezu is unknown; some say they were once been lieutenants of Asmodeus himself in the days before the fall, while other stories say it was thanks to nothing more than the idea of an especially forward-thinking pit fiend. After the occupation of Baator, they were chosen not to rule the plane (an achievement they wisely wished not to claim), but rather to rule its military, to continue applying their great skill in fighting off the tanar'ri. In this role they thrived for thousands of years before struck by the first loss; the public assassination of their leader, Cantrum, during a rally on the fields of Avernus by a crusading knight of Bahamut. Though greatly impacted by the loss of their leader, they have continued on in his name.
Each of the Dark Eight is assigned a specific duty towards the upkeep and performance of the Baator Legions. In addition, each is the head of one of the layer garrisons, the elite corps of the armies of Baator.
- Furcas - Head of Mortal Relations
- Furcas is charged with handling all interactions with the mortals that help bolster the ranks of Baator. He handles both planar recruitment and corruption of mortals on the Prime; in the purview of the latter, he directs all erinyes and falxugons currently active in finding suitable mortals to bring to Baator, alive or dead. He also directs actions against powerful mortals on the Prime serving the tanar'ri. In Baator, he leads the Creeping Cadre, garrison of Malbolge.
- Baalzephon - Supply Master
- Baalzephon's role is keeping all baatezu supply lines defended and active, and ensuring that the front lines get what they need. Well-connected, she and her underlings are responsible with contracting with the various multiversal trade guilds as well as agricultural and manufacturing concerns. She also directs mining and recovery operations on Acheron. In Baator, she leads the Gleaming Guard, garrison of Minauros
- Zimimar - Head of Morale
- Zimimar has the unenviable duty of ensuring the forces of Baator keep their spirits up, in both good times and bad. She does her best to keep good relations with baatezu at all levels, both to make sure they know their issues are heard, and to make sure she knows when those issues might begin to escalate; her network of informants spans even amongst the spinagons, and it's thanks to her that no baatezu rebellion or insurrection has succeeded in thousands of years. In Baator, she leads the Iron Defenders, garrison of Dis.
- Zapan - Head of Immortal Relations
- Where Furcas handles interactions with mortal beings, Zapan handles them with the immortal; chiefly the yugoloths, the modrons, and the powers. His role is very similar to that of Furcas, but the greater timescales involved and allowed grant a number of difference. Further, unlike Furcas, most of Zapan's dealings are held on equal footing; thankfully for him, he more than has the charisma to deal with hated foes without even a sneer. On rare occasions, Zapan has even dealt with the tanar'ri directly — he drafted the very short-lived Treaty of Ghoresh Chasm, an achievement that resounds even today. In Baator, he leads the Stygian Champions.
- Zaebos - Head of Promotions and Demotions
- Zaebos is responsible with keeping all records on every baatezu soldier across the entire multiverse, looking for the best of the best (and the worst of the worst) in order to ensure everyone is placed in a role best suiting their ability. He works closely with Zimimar in this respect, as being in the proper place in society is an important part of baatezu psychology. Out of all the Dark Eight, he perhaps has the most difficulty averting the politicking that runs rampant outside the Baator Legions, and if not for his position amongst the Dark Eight, he would likely have been killed by now a dozen dozen times over just through butting heads. In Baator, he leads the Maladominaar.
- Corin - Spymaster
- Corin heads the interplanar espionage network kept by the baatezu to ensure all tanar'ri plans get in their hands before they become a danger. Said to have infiltrators throughout the militaries of every plane, even amongst the Upper, it's rare that any event more important than a reassignment is able to escape his notice. In Baator, he leads the Serpentine Order, garrison of Cania.
- Dagos - Head of Strategy
- Dagos is in charge of directing actual combat operations in the Blood War. Directly below Dagos are the Three Commands of the Baator Legions, each led by three handpicked generals; Dagos' skill at finding strategic minds that rival his own is best exemplarized by his hand-selection of Bel from the ranks of First Command. In Baator, he leads The Few, garrison of Avernus.
- Pearza - Head of Research and Implementation
- Pearza directs all research into new means by which to destroy the tanar'ri and their forces. With interests both magical and technological, she has made much progress in developing methods for fighting demonic (and generally chaotic) entities; her largest coup was perhaps the creation of Baatorian green steel thousands of years ago, though it has long since spread outside the ranks of the Baator Legions. She also leads the Knoll of Blades, the kocrachon institute at which all new inductees to that rank learn their skills in medicine and torture. In Baator, she leads the Walkers in Fire, garrison of Phlegethos
- Faces of Evil - The Fiends, pg.29
- Fiendish Codex II - Tyrants of the Nine Hells, pg.38
- Hellbound - The Blood War: DM's Guide, pp.18-20