High Lords of Terra

The Spring 40,002 leisurewear collection from Maison Rouboute, modelled by (L-R): the Inquisitorial Representative, the Lord Commander Militant of the Imperial Guard, the Master of the Administratum (quill-glove: model’s own) and the Fabricator-General of Mars.

"Functionaries are like books in a library: the higher they are, the least they serve."

– Georges Clemenceau

"The measure of a man is what he does with power."

– Plato

"Behold! I've brought you a man!"

– Diogenes, handing Plato a plucked chicken (it makes sense in context)

The High Lords of Terra (aka “Asthmatic Assholes”) are the twelve members of the Senatorum Imperialis, the Council of the High Lords of Terra, and the rulers of the Imperium of Man in the Emperor's absence.

Overview

After Horus got his heresy on, the Emperor had to "ascend" the Golden Throne to keep himself alive. Since he wasn't dead, Roboute Guilliman reasoned that a new leadership was needed to guide the Imperium. He took the job of Lord Commander of the Imperium from Rogal Dorn and set up the High Lords from the old Council of Terra, inviting the heads of the Administratum, the Officio Assassinorum and the Adeptus Mechanicus to the table as well. As time went on, the Ecclesiarchy, the Inquisition, the Navigators and others were also invited. They seem to have an inordinate amount of influence over the Minotaurs.

While it's plainly evident that they are not making the Imperium better, there is some evidence that they may be making the Imperium worse than it actually needs to be (although whether this is due to malice or incompetence is anyone's guess, most people are betting on the latter). Exactly what they decide on isn't clear either. "Making decisions that affect the whole galaxy" sounds like a lofty purpose but really all the different departments seem to do things by themselves. The Space Marine chapters decide where they fight, the Inquisition governs itself, the Navigators govern themselves, the Administratum is like a machine just left running and doesn't even change gears... so unless they are just the people with the stamps to approve everything, we need some more fluff on what they are doing GW!

Well good news, I guess: as of 6th they are becoming more and more pro-active. AND in the new series The Beast Arises has them as the main characters and thus we can finally see how they run things. TL:DR oh, my God-Emperor, they're worse than the fans believed. During the War of The Beast, about half the High Lords were politicking and trying to use the biggest Ork WAAAGH! in their favour, getting billions killed along with dozens of Space Marine Chapters and even, it seems, a Primarch. The others tried to deny its existence entirely, leaving only the Grand Master of Assassins to deal with reality (go figure why he wanted to kill the jackasses). Funny enough they're also all portrayed as being very good at their jobs (the Imperial Navy High Lord is a skilled admiral, for example), they're just too focused on the interests of their own factions to work together. Of course, then the Grand Master of Assassins did The Beheading.

For the times the present day 41st millennium High Lords are mentioned, they tend to be treated with rather neutral tones. Typically the fluff only brings up their reactionary declarations to military matters and nothing about their politics, leaving their effectiveness and competence open to speculation. Given that Warhammer 40k is often about Your Dudes ("Your Setting" in this case), this is likely intentional.

The High Lords at the end of the 41st Millenium and the Rise of the Primarch

Watchers of the Throne: The Emperor's Legion has actually finally given us details about the High Lords during the Fall of Cadia, giving us a full list of names and going into detail on the actual politicking that the Lords get up to (Mostly concerning the Adeptus Custodes' deploytment, which dominates the first half of the book). Lev Tieron, the Chancellor of the Imperial Council of the time, notes that many of the High Lords he'd known were variously mad, obsessed, verifiably sociopathic, power-hungry, or some mix of the above - yet they were still the best qualified to do their jobs, even if the stresses caused them to burn out quickly. He even obliquely references the long-running fandom perception of them as useless idiots disconnected from the state of the Imperium, and notes that to be a understandable if wrong perception of them. Make of that what you will.

It also revealed that an important part of Terra's political background is the so-called "Static Tendency" - essentially the belief that since the Emperor had decreed the Council of Terra was the best way of running the Imperium, any proposal to deviate from this was only slightly better than outright heresy. In practice however, this was little more than an excuse not to upset the status quo or deviate outside from the comfortable norms. This was made blindingly clear in the lead-up to and especially in the aftermath of Cadia's fall and the subsequent return of the Primarch Roboute Guilliman, as the Static Tendency would thoroughly reveal itself as a hollow justification to cling to power by those who didn't deserve it, had failed in their duties, and were now willing to resort to treason and defying the will of the Emperor himself in order to retain their position and status. Needless to say, it didn't work.

Vaults of Terra reveals another far darker side to the High Lords. At least 3 of them were involved in a massive conspiracy to smuggle / lure (potentially a bit of both) a Dark Eldar Haemonculus onto Terra and into the Palace so that he could fix the Golden Throne / try to resurrect the Emperor. Insanity of the plan aside, it goes without saying that the High Lords had also given considerable "payment" to the Dark Eldar in exchange (read LOTS OF slaves and torture victims). They even contrived to attack various parts of the Inquisition in order to keep the secret. This worked surprisingly well, right up until the conspirators tried pulling the same trick with the Custodes who promptly carved them to pieces. Even whilst the Great Rift was unfolding, the conspirators still tried to keep covering their bases, ignoring the Astronomicon failing in order to cover up their dirty laundry. Far less doddering incompetence and far more sneaky bastarding evil.

As of the Gathering Storm, Roboute Guilliman came back to Terra and proceeded to go full 'Powerfisting-mode' at several members of the High Lords following an attempted civil coup d'etat against him, replacing them with people Papa Smurf (seemingly - see below) trusted in the capabilities and competences of. The other High Lords who were not removed were given a mean look by the Blue Wonder and were essentially given a second chance with Robby keeping a close eye on them from afar, and the Talons of The Emperor keeping a much more immediate (and stabby) eye on them from nearby. Regardless of affiliation, the Council was rocked by the change to thousands of years of them on top, as well as the colossal waves of reforms put in place by Bobby G. Some of them got the message. Some did not.

Corvus Corax said in Corax: Lord of Shadows of the Primarch series that "Few are as short-sighted as those about to lose power" and by Christ the Emperor is that an apt assessment, and one that applies well to the High Lords. Given that this was an express order issued directly by The Master of Mankind himself to his own son and was confirmed by the Captain-General of the Custodes, who himself was now a High Lord, that really should have been the end of it many times over. Instead it lasted about as long as it took for Guilliman to head off on the Indomitus Crusade, whereupon several High Lords (and two prior incumbent deposed by Guilliman) attempted to stage a coup against him in absentia; this involved sapping away manpower and resources from desperately needed areas (including the entire Minotaurs Chapter) while allowing chaotic cults to flourish on Terra, to grant themselves the forces and pretext necessary to take over. Unfortunately for them however, The Custodes, Sisters of Silence, Assassins, and later the Imperial Fists were having absolutely none of it and promptly intervened.

Immediately after the couple of hours it took for the Custodians to notice, the traitor High Lords were permanently ventilated, the Minotaurs forced to obey by the replacement Mistress of the Administratum, Violeta Roskavler, and replacement Lords were drafted in.

It's later revealed that Guilliman, Trajan Valoris, and Violeta Roskavler predicted that something like this would happen, so at least they're aware of what the council is like. It also adds an interesting possibility that Guilliman deliberately stacked the council with potential liabilities/left them in (he could have flooded the first redraft with reformers, but didn't) so that he could later replace them with the competent loyalists after those tendencies were proven suspect got themselves killed along with the Cults they had let form, purging Terra of traitors of both the Chaotic and power-hungry moron kinds in a matter of hours.

That's legitimately clever.

Members

The High Lords are theoretically a dynamic body of 12 (or 13-14; see below) members that changes based on the needs of the Imperium. That this was the same number of members as are on the Skaven Council of Thirteen until the Great Rift is something we're probably not suppose to notice. Or they're both a reference to Jesus and the 12 Apostles. Anyway, there's supposed to be a whole Senatorum Imperialis, but the 12/13 are the guys that actually matter, plus a few more with similarly but not-quite as important roles being given descriptions.

Any names in bold denote the current holder of the listed seat.

Nine Permanent Members

In reality, the same nine old fucks decide everything millennium in and millennium out because they/who they represent are just so influential, leaving only 3 seats up for grabs. These nine guys are:

• Ecclesiarch: The Space Pope, the leader of the Adeptus Ministorum, or Ecclesiarchy. Was granted a seat in M32 for the first time, seat which became permanent three centuries later. During the Age of Apostasy, the Ecclesiarch briefly usurped the Master of the Administratum as most powerful High Lord. Goge Vandire solved that problem by being head of both, then went nuts with power and had to be killed by the proto-Sisters of Battle after Custodes informing them of the Emperor's will that Vandire must die (incidentally allowing the Sisters to prove their loyalty and to be accepted as the official Ecclesiarchy armed force through the pre-arranged exact wording of "no men under arms" in the reform laws by Vandire's replacement Ecclesiarch Sebastian Thor and the other High Lords at the time).
  • As of M41/M42, the Ecclesiarch is considered tied with the Fabricator-General and the Grand Master of Assassins for third most powerful High Lord. Baldo Slyst was fired by Guilliman from this post, and joined in Irthu Haemotalion's failed Hexarchy coup and was shot by a Vindicare Assassin. Baldo's replacement Eos Ritira is the current Ecclesiarch and she is seen as a reformist.
• Fabricator-General of Mars: The head of the Adeptus Mechanicus will occasionally take time from meditating on the Omnissiah or running his/her own nation to help run the Imperium. The only member of the 'High Twelve' that isn't regularly stationed in the Palace itself, mostly due to practical reasons: the most recent one had great difficulty attending meetings in the 'flesh' owing to being augmented to the size of a small building. Luckily, Mars is close enough to Terra to allow for old-fashioned vox communication so it is in the end but a minor hassle. He also seems to have an unspoken role of being the one to lead repairs and maintenance of the Golden Throne (though it seems he doesn't actually know how to work the thing). Despite the current holder, Oud Oudia Raskian, being thoroughly opposed to the Custodes being allowed off-world and having collaborated with others to smuggle a goddamn Haemonculus onto Terra (to technically do his job in fixing the throne), he's still around, probably because Rowboat Girlyman can't get rid of him without pissing the AdMech off or having no one but Belisarius Cawl, who is too radical to hold the post, as his replacement.
• Grand Provost Marshal: Head of the Adeptus Arbites. Makes sure the Imperium's myriad jackboots know whose skulls to bust. Often the head of the Arbites on Terra, which is actually a pretty good qualification, as Terra is one mean beat. Aveliza Drachmar was the previous Grand Provost Marshal; upset by the Custodes being sent on missions away from Terra (claiming that the Lex Imperialis and its restraints were inviolate despite the fact there were literally daemons on Holy Terra, Jesus Christ you brainless bitch), she joined the attempted coup and thus got shot by a Vindicare Assassin on orders of Fadix.
• Inquisitorial Representative: A member of the Inquisition, sent to insure that the Emperor's pet psychopaths are up to date on what laws to enforce, which can be difficult given how factionalized the Inquisition has been shown to be in fluff. An Inquisitor's term is 5 years after which he/she has to step down to make place for another. It is interesting to note that while there is hefty political competition for the other seats, the seat of Inquisitorial Representative carries little merit because it prevents an Inquisitor from carrying out his primary duty: to directly protect the Imperium from its many enemies by working in the field (ie, running their secret pet projects). So more than a few Inquisitors would see the posting more as being assigned to desk duty rather than being in the field, and the decentralized nature of the Inquisition meaning they technically gain no greater authority within the organization (they are a representative, nothing more). Some Inquisitors instead view the position as impromptu shore leave before getting back to (dirty) business. They are selected, often unanimously, from Inquisitor Lords from the sectors near Terra, granting the individual the title of Inquisitor Lord Terra even after his service ends. On the plus side however, the Inquisition mostly runs on an "influence" system, and becoming the Inquisitorial Representative gives the Lord Inquisitor in question a substantial boost in influence. Furthermore, one almost never becomes a full-fledged Inquisitor (let alone a Lord Inquisitor) without a lot of hard-earned field experience doing dirty work in the nastier parts of the galaxy, so the Inquisitorial Representative is likely to be one of the more competent and practical members of the bunch (whether the Inquisitor in question is entirely sane and rational is another matter altogether). However, in rare cases the Inquisition is too busy to send a representative because Xenos and Chaos incursions are too numerous. It's been noted by Imperial historians that whenever there wasn't a representative from the Inquisition on the High Lords to keep things in check, bad things happened.
  • The current representative is Kleopatra Arx, who has held the position since before Guilliman's return, and she remains there still. As far as the Inquisition goes, Arx is refreshingly competent and reasonable (if a bit appropriately cold and pragmatic), and thus was one of the relatively few High Lords that needed neither a booting nor scolding from Guilliman. She was present when the coup attempt took place, but was having none of it, and may well have shut it down herself had others not already been handling it (thus being another prime example how idiotic the coup attempt really was in the grand scheme of things).
• Grand Master of Assassins: Perhaps equally surprisingly, the other High Lord who often acts as a check and balance for sanity (as The War of The Beast demonstrated) is the head of the Officio Assassinorum, and an informal watchdog of the Council. The Grand Master is constantly watched by the other High Lords, both because the Assassins are fucking scary and out of concern that he might assassinate the others - mostly because one Grand Master did just that, though they really had it coming. Funny story. It's seen as tradition for the Master of Assassins to send back the corpses or heads of the other High Lord's spies periodically, as a polite reminder that they do not tolerate the other lords messing with their business. His situation in the council is a bit complicated: theoretically, the Officio Assassinorum is a branch of the Administratum, so this guy has the Master of the Administratum as his boss. Also, he needs the whole council's approval to send out his assassins away from Terra after a target as per Big-E's edict. On the other hand, any attempt by the Master of the Administratum (or any other High Lord) to boss the assassins around is likely to result in death due to be seen as trying to pull a Goge Vandire; so the Grand Master has a lot of practical independence, politically speaking. Also meaning due to his highly useful organization and inevitable dirt he would have on other high lords makes the Grand Master far more politically powerful than what would be expected of a relatively small organization.
  • According to Lev Tieron, the post of Grandmaster is frequently behind the periods of unrest within the High Lords - Drakan Vangorich was merely the best known. That said, the incumbent, Fadix, who despite being sceptical of Guilliman's ability to prevail, is almost single-handedly responsible for saving Terra from the aforementioned coup attempt - he goaded the seditious High Lords into showing their hands by offering them the assurance that the ultimate sanction was on their side, thereby causing the unrest and rebellion so that it could be flushed out once and for all (the Custodes were a mix of busy elsewhere and too busy laughing their asses off at the sheer idiocy of the plot before them). Fadix's personal inclination to the Static Tendency aside, he clearly takes his role seriously, so when the coup came around, his belief in the law and his allegiance to the Master of Mankind superseded all else, thus he still holds the post. As of M41/M42, the Grand Master is considered tied with the Fabricator-General and the Ecclesiarch for third most powerful High Lord.
• Master of the Adeptus Astra Telepathica: The guy/gal in charge of the selection, training, and use of Astropaths and other various kinds of sanctioned psykers within the Imperium. Making sure the Imperium's giant network of psychic email servers don't go to shit is so damn important to keep it running that they gave them a permanent seat. It was seated by Zlatad Aph Kerapliades during the 13th Black Crusade.
• Master of the Administratum: The head of the Imperial bureaucracy. While the Master of the Administratum is an equal with the rest of the High Lords on paper, in practice he/she is considered the "head" of the Senatorum and most powerful of the High Lords due to how integral the Administratum is to the functioning of all the other organizations and the Imperium itself, and they are fucking territorial about that. With the Emperor appointing his son Imperial Regent, the Master of the Administratum is now the second most powerful High Lord, with the Fabricator-General, Ecclesiarch and Grand Master of Assassins now fighting for third most powerful. Irthu Haemotalion was very upset about this after being fired and actually attempted a coup on Guilliman only to get killed to death by Fadix along with his fellow traitors/conspirators (he was also shot by a Vindicare). He was replaced by Violeta Roskavler, who has a reputation of being a hard working logistical genius. And just like Guilliman's brother, she hails from Inwit. It's eventually revealed that she, Valoris, and Guilliman knew Haemotalion would try a coup attempt like this and planned to use it as an excuse to cleanse the capital of any further political liabilities (so Haemotalion turned out to be pretty useful in a backhanded way). Roskavler was previously the Master of the Departmento Munitorum so she is certainly on the more militarist wing of the political establishment.
• Master of the Astronomican: While the Adeptus Astronomica isn't nearly as large or influential as the other members' branches, they keep the light of the Astronomican burning. The Astronomican in turn keeps the Imperium from collapsing, and every other High Lord from being fucked inside out by daemons on their way to meetings, so they let this guy have a chair along with his pal/rival from the Adeptus Astra Telepathica. Because the Adeptus Astra Telepathica serves as the Astronomican's recruitment arm, having these two members disagree on policy is uncommon, but they are legally independent bodies (each of equal rank with the Administratum), so it's certainly possible. The previous one died during the Chaos (of both capital C and regular c varieties) of the Long Night and Guilliman used the opportunity to stack the High Lords with competent loyalists further after Fadix's purge of the morons who tried to rebel against a fucking Primarch already emptied several slots (along with some firings that lead to said coup attempt in the first place). Now chaired by Lucius Throde who prior served under the High Lord Kerapliades as part of the Adeptus Astra Telepathica.
• Paternoval Envoy: Representing the Navis Nobilite, the third of the guys to get a seat because otherwise the Imperium would collapse without faster than light travel and communications. This guy/gal makes sure that the Navigators have a say in what's going on, so they won't get declared abominations of the holy human form. Unlike the other posts, s/he is not the head of the combined Navigator houses, but a representative from the Paternova, the currently effective head house of the Navis Nobilite. The Paternova cannot attend meetings because s/he stays in the Palace of the Navigators due to...changes they undergo upon assuming the post, which would cause mass rioting among the populace questions among the less-informed. As a result, the Paternoval Envoy is a young, still fully-human looking Navigator (except for the third eye, of course) and usually chosen from a weak house who couldn't upset the balance of power among the Navigators should the position go to his head (the fact they can be quickly and quietly removed if they fuck up is wholly incidental.) Theoretically, the Paternova's rank equals that of the other two people who run the Imperial Fleet (both of whom sometimes also get seats - see below), but they are just too practically important and significant for anyone to really claim they outrank them. Kadak Mir serves as the current envoy by order of Guilliman, replacing Uila Lamma. It is suspected Lamma was removed for advocating for too much reform to the Imperium's laws, which went against Guilliman's more cautious measures.

Three Dynamic Members

The remaining three fluid positions are held by people either beholden to one or more permanent members, or by people so powerful they just walk in to take a seat. Needless to say, they keep the seat as long as they, or their allies, are strong enough to hold it. They include:

• Independent
  • Captain-General of the Adeptus Custodes: He's kind of a special case: by Big-E's ancient but never overturned decree, the Captain-General speaks with His voice at all times, unless Malcador or Himself are present. This would technically make the Captain-General the leader of the Imperium as a whole (with Malcador ultra-dead and Big-E unable to communicate) but since that setup was (even more) horribly impractical, a compromise was found. In normal circumstances, The 12 High Lords and the rest of the Senatorum Imperialis deal with leading the Imperium while the Captain-General and his fellow Custodes ensure the security of the Imperial Palace and the Emperor; both institutions working in tandem without much interaction or interference. However, whenever the Captain-General decides he needs to join the discussions (for instance, to make sure the High Lords keep their shit together or to tear the next Goge Vandire a new asshole), a seat is freed for him on the spot until whatever situation made him pop his head in is resolved. While he generally despises playing politics with mere mortals whenever he does attend a meeting, all the other High Lords shut their flapping gums and pay close attention to what he has to say (because, y'know, the guy is considered one step below the Big E Himself, and disrespecting a person who can mulch anything short of a Greater Daemon is a Bad Idea). The current Captain-General is Trajann Valoris, currently one of four active High Lords (aside from Guilliman, Dante, and Morvenn Vahl) known to have gotten a model and rules for the tabletop.
• Administratum Subordinates:
  • Chancellor of the Estate Imperium: The Imperium's head paper pusher. Seriously, they're a glorified secretary. The most useless of the High Lords, and only gets on if the Master of the Administratum feels he needs another vote on things and can muscle one of their underlings in. (Given the name, they probably oversee the treasury of the Imperium as a whole and possibly the tithes.) The previous holder of the office was Brach, who died in 999.M41 before the reforms of Guilliman.
  • Lord Commander Militant of the Imperial Guard: The leader of the Emprah's hammer. Nominally in charge of every man, woman, and child in the Imperium with a flashlight to point, although the bureaucratic distances and sheer, incomprehensibly large numbers of personnel involved means that they mostly dictate uniform and grooming standards, and maybe operational doctrine if the bigwigs at the Departmento Tactica are feeling indulgent. With the Master of the Administratum in charge of their record keeping and the Chancellor of the Estate Imperium in charge of their bank account, though, The Lord Commander Militant hasn't got as much of independent swing as one might think. Still, someone needs to give career bureaucrats some form of advice in military necessity, therefore allowing them a seat. The previous holder, Mar Av Ashariel, was among the failed Hexarchy plotters and was killed by a Callidus Assassin. The late Lord Commander Militant gained the High Lord seat from Speaker Dhanda by Guilliman to better military coordinate the Senatorum.
    • Lord Commander of the Segmentum Solar: A direct underling of the Lord-Commander Militant that often only gets a seat whenever the military situation goes from "shitty" to "completely FUBAR" and there's a need for some crusade or other to set things a little less wrong in the Imperium. They're the commander of the Imperium's forces (those that listen to the military bureaucracy anyway) in charge of guarding humanity's chewy centre, Segmentum Solar. One of the more notable examples would be the awesome (both in the classic and the contemporary sense) Lord Solar Macharius. The current Lord Commander of the Segmentum Solar is Arcadian Leontus, who is no slouch himself.
  • Lord High Admiral of the Imperial Navy: Discards the shiniest of flying space cathedrals in favour of the shiniest of desks. Like their counterpart(s) in the Imperial Guard, they often gets a seat when there is some Ork WAAAGH!/Tyranid Fleet/Black Crusade/Tau Expansion/etc. happening. Unlike their counterpart, though, they aren't dependent on the Chancellor for money, but they are dependent on the Navigator houses and the Astronomican for navigation and on the Adeptus Astra Telepathica for communications. As a result, they don't have as much wriggling room as one might think either, but the same thing about military necessity also applies here. The previous holder of the post, Merelda Pereth, was among the failed Hexarchy plotters and was killed by a Callidus Assassin.
  • Speaker for the Chartist Captains: Spokesperson of the Merchant Fleet, this High Lord defends the interests of the various trade captains within the Imperium. They are similar to but less powerful than Rogue Traders, but make up about 90% of the Imperium's spacefaring capability. They might not look like much at first glance, but along with the various Psykers above they're the glue keeping the Imperium together by making interplanetary commerce possible at all (which is a matter of survival for many, many planets), so they too get a voice in running things when there's a seat free (read: in those times of relative calm when the military situation is galactically stable, so the decades of this seat being free can probably be counted on one's hands). There are four levels of Merchant Charters, from flying fixed and limited routes to being allowed to travel through all of Imperial space within the Segmenta. Kania Dhanda is the current Speaker, and she works to rebuild the Imperium's shattered trade routes from the Great Rift at the Nexus Axiomatic fortress after being retired from the High Lords by Guilliman.
• Ecclesiarchy Subordinates
  • Abbess Sanctorum of the Adepta Sororitas: The head of the Adepta Sororitas. The only member of the High Lords who is a woman by default, she is elected from the leaders of every order of the Sororitas. Like the Inquisitorial Representative, there is no real race for this position. It is, in fact, considered a penance to become the Abbess Sanctorum, which, given the other assholes in the Senatorum, is not that far from the truth. Before the Abbess is formally inducted, she is to take a pilgrimage to San Leor, the homeworld of the Daughters of the Emperor. The would-be Abbess, Sister Sabrina of the Order of the Ermine Mantle, disappeared during her pilgrimage. Tradition dictates there cannot be another Abbess elected until the current one's fate has been determined, so the seat of the Abbess remained empty for the longest time. Post-Great Rift, Celestine and her forces were able to find Sabrina trapped fighting off waves of Daemons on San Leor. After fighting them off, she was finally able to take up her seat. Later, Guilliman was able to get the newest Abbess to support his purge of Holy Terra’s more corrupted dredges in society while she also urged the Assassin to send a Vindicare agent on a hunt against an Ork Warboss that had looted a Shrine-World. The current Abbess Sanctorum is Morvenn Vahl. While it's uncertain what befell of Sabrina (actually San Leor is still occupied, she stayed), Vahl was elevated here by the advisory of Guilliman and the Custodes (and by the Ecclesiarch, who mistakenly expected that her youth would make her easily manipulated). She's currently helping with the ongoing war in the Charadon sector against Typhus.
  • Cardinal of the Holy Synod of Terra: Some old fart from a group of old farts who spend all their time arguing about slight deviations in doctrine. Their only useful function is electing the head of the Ecclesiarchy who gets them their chair on the council. Mentioning that this is a conflict of interest is considered heresy. The Holy Synod is an organization that primarily concerns itself with running the church on Terra, so in theory, it can provide up to 3 Cardinals to fill all the vacancies, though this would never fly even in peacetime.

The Thirteenth (and Fourteenth) Lords

The position of Lord Commander of the Imperium's armed forces was one that Rogal Dorn was originally invested with as the coordinator of the loyalist war effort during the Horus Heresy. Roboute Guilliman took it from him at some point afterwards and used the title Lord Commander of the Imperium (as the first man to command the forces of the Imperium in its entirety) where it became synonymous with Lord Guilliman even past his injury and eventual removal by his brother Fulgrim (presumably because no one had the balls to remove the plaque from the door).

The position lasted at least until the 32nd Millennium and was the de jure leader of the Senatorum Imperialis, and on paper was the commander of the entirety of the Imperium's military forces. We say "on paper" because the last dude prior to Chapter Master Slaughter Koorland was a puppet of the other agents of the senate, and was generally incompetent. Koorland's successor, Maximus Thane, also took the role of Chapter Master of the Imperial Fists, and was presumably the last to hold the title, because after issuing a series of standing orders, he decided to leave Terra and rebuild the broken Imperium following the War of The Beast, only returning to deal with The Beheading. The post appears to have been abolished at some point after this.

As of the closing years of the 41st millennium, Roboute Guilliman is back as the Lord Commander again, mostly because nobody else available could be trusted with a job that important, but also significantly due to the fact that nobody dared to say no to him when he announced he was taking his seat back. At least, not to his face. Several of the High Lords did, however, attempt to stage a coup, which was foiled by the Adeptus Custodes and Grand Master Fadix of the Assassinorum who had the four (well, three, he double agented and backstabbed them) serving and two fired High Lords attempting the coup simultaneously killed by his subordinates. He also appointed Dante as Lord Regent of the northern half of the Imperium and as mentioned replaced the Master of the Astronomican, who had coincidentally died due to the Long Night in the immediate aftermath of the Great Rift opening.

The Senatorum

As mentioned, the High Lords of Terra are a dynamic organisation, that shifts and changes according to the politics of the day. The seventeen Lords listed above in no way represent the entirety of Imperial government, nor do those Lords who don't get a seat on that particular day lose their ability to have their voices heard or impact policy; the Senatorum actually consists of tens of thousands of politicians, all with their own voting rights and agendas. However, the full body virtually never meets in session, and those positions that fall out of eminent favour simply don't occupy seats on the "High Twelve", which also comes with a reduction in privileges, including the right to give orders to Custodians (they make the distinction between High Lords and those of the High Twelve + Rotating Greater Lords not currently voting). That right to give orders, however, is rendered moot within the Imperial Palace, with the obvious exception of the Captain-General. Known lesser lords and positions are as follows, note how their jobs when described are relatively important to the general situation as well rather than being some nobody on present to raise numbers:

• Chancellor of the Imperial Senate: A rank that exists outside of the High Lords, who acts like the presiding officer of the council. Their job is sometimes more arduous than the actual High Lords, as they have to essentially herd, bully, intimidate, sweet talk, and basically cajole all twelve into regular sessions, as well making sure the process doesn't turn into an eternal game of 'pass the buck'. They are also meant to be as politically neutral as possible, which considering how much cross intent and vested interest floats around the council is either very easy or extremely hard. Lev Tieron was the previous holder and retired during Guilliman's reforms citing old age. His protégé and successor Anna-Murza Jek was instrumental in the foiling of the Hexarchy plot and is currently in office.
• Commandant of the Schola Progenium: The head of the Schola Progenium, and the joint senior-Commissar of the Imperium, presumably with the head of the Commissariat. Makes sure the new generations properly worship the Emprah and properly hate anything the government does.
• Chirurgeon-General of the Orders Hospitaller: The head Medicae of the Imperium. Though part of the High Twelve in the days of the Emperor, the Chirurgeon-General lost their status as a rotating member of the High Lords after the Horus Heresy, which goes to show how little a priority healthcare is in the Imperium, though for what its worth the post remained as major lesser High Lord.
• High Lord of the Imperial Chancellery: The head of the Imperial Chancellery. This is the person who runs the offices of the Adeptus Terra and is essentially the superintendent of the Imperial Chancellery (Custodian interference and forbidden areas of the Imperial Palace aside). Originally part of the High Twelve, it lost its status after the Heresy and remained a major lesser High Lord.
• Lord Constable of the Synopticon: The head of the Synopticon. What exactly this does is unknown, but "Synopticon" is a word that means "Surveillance of the few by the many"; as his title is "Constable" that presumably makes him some kind of rule enforcer for the Senatorum itself, making sure proper procedure is followed while being more directly involved than the Chancellor. Other guesses are that he's the leader of the space CIA as opposed to the Inquisition's space FBI, or that he acts as the security chief for the Imperial Chancellery.
• Mistress Plenary of the Catacombs: The person overseeing the Catacombs. What exactly that means is unknown, but given what is usually placed in the catacombs of the Imperial Palace, it probably isn't pretty.

These six are generally important to the galactic situation or at least Terra's (or the Chancellery within the Imperial Palace itself) and if any of the lesser lords outside the "can be one of the big thirteen" group are in an important but not-everyone is present level meeting its them. Other posts don't have names in the fluff at this time. Speculatively, the Segmenta and particularly important Sectors might have representatives.

When it is expedient or politically advantageous to do so, the High Lords may choose to take seats in various chambers around the Imperial palace. While some chambers are large enough to seat the whole of the senate and then some, others are barely larger than an office, where lesser lords get excluded (save the above posts who as mentioned previously are the most likely of the lesser lords to be present in big deal government meetings which involve those outside the High Twelve but not the other Senatorum politicians, alongside the rotating greater lords).

Finally, the actual bureaucrat in charge of the Senatorum itself, the Chancellor of the Imperial Council (currently Anna-Murza Jek, protege and successor to the retired Lev Tieron), should be detailed further. This is not a High Lord of Terra, but still wields great political power as being in charge of the top level bureaucracy allows them great influence and power as was seen when Jek became suspicious of the fired Master of the Administratum and Ecclesiarch plotting against Guilliman. She was critical in arranging for the traitors to spring their coup early and getting them killed by Grand Master of the Assassins Fadix backstabbing them.

Trivia

• The authors of the Horus Heresy series are collectively referred to as the "High Lords of Terra" on Black Library's blog. According to Dan Abnett, this is intended as self-deprecation. Yes, even the makers of 40K canon think the High Lords of Terra are useless.
• All tea and biscuits are the property of the High Lords of Terra and no one else. They are needed for the constant meetings the High Lords have (most likely to decide what colour to paint the Imperial Palace's walls this season).Of course it should be GOLD, the Emprah's favorite!
• The High Lords do decide on foundings of Space Marines and assign the title of Warmaster to special individuals undertaking Imperial crusades. However considering how many chapters turn renegade or do their own thing and how many crusades seem to fall into failure, this could be further proof of the High Lords' collective uselessness.
• With Papa Smurf as defacto leader of the entire Imperium again, the usefulness of the High Lords have went up a reasonable notch. Mostly because most of them were sacked and replaced after they were dumb enough to try and stage a coup against Roboute freaking Guilliman.
  • Actually only two were sacked. Four more joined the treason plot. The Grand Master of Assassins backstabbed the plotters and killed the other five and kept his post.
• Their Fantasy equivalent, the Council of Thirteen manages to be more effective and productive despite being run by megalomaniac backstabbing ratmen drug addicts.

See Also

• Writefaggotry from /tg/ on the High Lords